10 possible Senate retirements
© Greg Nash

Capitol Hill isn’t a happy or easy place to be these days, and several senators could be eyeing the exits ahead of 2016. 

While no official retirement statements have come out of the upper chamber yet, it’s safe to assume that many politicians are using the holidays to ponder their future. 

Here are 10 senators who could potentially step down after the 114th Congress.

Sen. Barbara BoxerBarbara Levy BoxerKamala Harris endorses Gavin Newsom for California governor Dems face hard choice for State of the Union response Billionaire Steyer to push for Dem House push MORE (D-Calif.)

Boxer’s fundraising efforts have lapsed, stoking speculation that the longtime liberal senator is ready to hang it up. 

According to her latest Federal Election Commission filings, Boxer has less than $150,000 in her campaign account after a quarter in which her contributions fell short of $12,000. 

That’s in stark contrast to her fundraising efforts from the same quarter ahead of her successful 2010 reelection, when she raised $2.6 million and sat on more than $3.6 million.

Boxer, who is 74, told The Associated Press earlier this year that she’ll make an announcement in early 2015.

If she does retire, Democrats' deep bench of diverse potential candidates includes Lt. Gov. Gavin Newsom, Attorney General Kamala Harris, Los Angeles Mayor Eric Garcetti and former Los Angeles Mayor Antonio Villaraigosa. 

Sen. David VitterDavid Bruce VitterTrump nominates wife of ex-Louisiana senator to be federal judge Where is due process in all the sexual harassment allegations? Not the Senate's job to second-guess Alabama voters MORE (R-La.)

Vitter announced earlier this year that he intends to run for governor of Louisiana in 2015 to succeed term-limited Gov. Bobby Jindal (R-La.). 

Since it’s a year before he’d be up for reelection in the Senate, if he wins, he could retire from the Senate and appoint an interim replacement to his seat in the upper chamber. If he loses the governor’s race, he could still run for reelection to the Senate in 2016.

Analysts say Vitter, who coasted to reelection in 2010 despite previously having admitted to being a client to the infamous “D.C. Madam,” is the overwhelming favorite to take the governor’s mansion in a state that has turned deep red in recent cycles. 

However, the Louisiana gubernatorial race is a jungle primary, so Vitter’s toughest challenge could come from another Republican. Strategists say Vitter would easily dispatch of any potential Democratic foes, but if none make it to the runoff, they say anything could happen between two Republicans going head to head. 

Rep. John FlemingJohn Calvin FlemingCoast Guard suspends search for missing Ohio plane Freedom Caucus member to bring up bill on impeaching IRS chief GOP seeks to make it 52 MORE (R-La.) has also expressed interest in the seat, and Rep. Charles BoustanyCharles William BoustanyDems face hard choice for State of the Union response Americans worried about retirement should look to employee ownership Top Lobbyists 2017: Hired Guns MORE Jr. (R-La.) has also been mentioned. Republicans in the state also have a deep bench of potential state-level candidates. 

Sen. Marco RubioMarco Antonio RubioColbert: Students taking action on gun violence 'give me hope' Lawmakers feel pressure on guns Florida lawmaker's aide fired after claiming shooting survivors were 'actors' MORE (R-Fla.)

Rubio’s Senate career is at a crossroads.

He’s been laying the groundwork for a presidential run, but Florida state law prohibits him from running for the Senate and White House at the same time. Unlike Sen. Rand PaulRandal (Rand) Howard PaulDem wins Kentucky state House seat in district Trump won by 49 points GOP's tax reform bait-and-switch will widen inequality Pentagon budget euphoria could be short-lived MORE (R-Ky.), who is seeking a work-around to the same conundrum in his home state, Rubio has said he won’t seek both. 

That means if Rubio takes the presidential plunge, he’ll have to retire from the Senate.

If that’s the path he takes, Florida would become an instant toss-up. Democrats are already eyeing two House members from red districts in the state — Rep. Patrick Murphy and incoming Rep. Gwen Graham — as potential challengers to Rubio or whoever the GOP puts forth to run for the Senate in 2016. 

Political watchers, meanwhile, have no idea whether Rubio will run for president. They believe he’s a rare political talent, but his mentor, former Florida Gov. Jeb Bush, is likely running for president, and the two share many of the same donors and supporters. 

Rubio has maintained Bush’s decision won’t factor into his own, but polls show that most Republicans right now would side with Bush over Rubio.

Still, Rubio is a popular rising star in the party, and he has options beyond 2016. He could run for governor to succeed Gov. Rick Scott (R) in 2018, and Florida’s other Senate seat, currently held by Sen. Bill NelsonClarence (Bill) William NelsonGingrich says arming teachers only long-term solution to school shootings Florida students turn to activism in wake of shooting CNN invites Trump to town hall with parents, students of Florida high school MORE (D-Fla.), will also be up for grabs that year. 

Sen. Joe ManchinJoseph (Joe) ManchinPavlich: The claim Trump let the mentally ill get guns is a lie Toomey to introduce bill broadening background checks for firearms Scott Walker backs West Virginia attorney general in GOP Senate primary MORE (D-W.Va.) 

Manchin, a centrist Democrat from a red state, has been vocal about his frustrations with gridlock on Capitol Hill and the leadership in his own party. 

That could have him eyeing a return to his old job as governor of West Virginia, a post he held from 2005 to 2010.

“There is definitely that consideration," he told The Register-Herald in November. "If I don't see the opportunities to really help my country and my state, and things just stay the same and we continue to hear the rhetoric, if it's the same-old same-old, it's not a place I'd desire to be.”

"If there is an opportunity in West Virginia and the people would want me to come back home, I would definitely consider that move," he added.

The Hill reported earlier this year that Manchin gave generously to state officials from his campaign account in 2014, potentially laying the groundwork for a return there.

Democrats would be hard pressed to hold Manchin’s seat should he leave Washington.

In 2016, it will have been 20 years since West Virginia voted for a Democratic presidential candidate, and Republican Sen.-elect Shelley Moore CapitoShelley Wellons Moore CapitoAt least Alzheimer’s research is bringing Washington together Overnight Tech: Intel chief says 'no doubt' Russia will meddle in midterms | Dems press FCC over net neutrality comments | Bill aims to bridge rural-urban digital divide | FCC to review rules on children's TV Senators offer bill to close rural-urban internet divide MORE crushed her Democratic opponent in 2014 by nearly 30 percentage points.

Sen. Harry ReidHarry Mason ReidWATCH: There is no Trump-Russia collusion and the media should stop pushing this The demise of debate in Congress ‘North by Northwest,’ the Carter Page remake MORE (D-Nev.)

Reid has said he’s running for reelection and reports indicate he’s beginning to staff up, but would the 75-year-old outgoing Senate majority leader stand in for another fight if he was a long shot?

In 2010, Reid survived the Tea Party wave in large part because of the disastrous candidacy of GOP nominee Sharron Angle. But in 2016, he’ll be a top target for Republicans.

Reid is underwater among Nevada voters, and if Gov. Brian Sandoval (R-Nev.) jumps in, the longtime Senate Democrat would become an instant underdog. 

Reid, who has more than $1.5 million in cash on hand, has experienced backlash from some centrists in his party who are ready for new leadership after November's losses.

Sen. Dan CoatsDaniel (Dan) Ray CoatsTop state election official questions why Trump is downplaying threat of Russian election interference: report Russian bots turn to gun control after Florida high school shooting: report The case alleging Russian collusion is not closed MORE (R-Ind.)

Coats has retired once before, spending more than a decade outside of Washington before returning for a third term in 2010. 

He’s expressed frustration with the gridlock in Congress, but earlier this year, he told The Elkhart Truth that a Republican majority would factor into his decision to run for reelection.

Republicans took the Senate in 2014, but that majority could be short-lived. Coats presently has less than $800,000 in his campaign account.

Sen. John McCainJohn Sidney McCainLawmakers worry about rise of fake video technology Democrats put Dreamers and their party in danger by playing hardball Trump set a good defense budget, but here is how to make it better MORE (R-Ariz.) 

The 2008 GOP presidential nominee has openly mulled retiring when his term ends in 2016. 

“The president and I, he's in his last term, I'm probably in mine, the relationship we have had over the past three years is quite good,” he told The Wrap in an interview last year, adding that he didn’t want to be “one of these old guys that should’ve shoved off.”

He’s since changed his tune, telling The Arizona Republic that he’s “seriously considering” and “leaning towards" running for reelection.

Still, the 78-year-old knows what kind of challenges lie ahead. He’s acknowledged that he’ll likely get a primary challenger from the right, and if that’s not something the no-nonsense five-term senator wants to deal with, he could shove off sooner rather than later.

Sen. Chuck GrassleyCharles (Chuck) Ernest GrassleyPavlich: The claim Trump let the mentally ill get guns is a lie Congress fails miserably: For Asian-Americans, immigration proposals are personal attacks Grassley, Dems step up battle over judicial nominees MORE (R-Iowa)

Grassley told a public TV station in Iowa earlier this year that he intends to run for reelection in 2016. He said that with Sen. Tom HarkinThomas (Tom) Richard HarkinTrump should require federal contractors to follow the law Orrin Hatch, ‘a tough old bird,’ got a lot done in the Senate Democrats are all talk when it comes to DC statehood MORE (D-Iowa) retiring at the end of the year, he didn’t want to leave the Hawkeye State with two junior senators. 

Still, Grassley would be pushing 90 by the end of his next term, but he proved in 2014 he can still handle the rigors of the campaign trail. He crossed the state on behalf of Republican candidates, and he’s an avid runner to boot. The Republican has more than $1.7 million in his campaign account. 

Sen. Patrick LeahyPatrick Joseph LeahyGrassley, Dems step up battle over judicial nominees Popular bill to fight drug prices left out of budget deal Judiciary Dems want public hearings with Kushner, Trump Jr. MORE (D-Vt.)

Leahy told reporters at the end of 2013 that the government shutdown convinced him that he needed to run again to ensure that there are enough “grown ups” in Washington to run things.

But at 74 years old and with four decades in Congress behind him, he’s among the most senior members in the upper chamber. He’ll also be losing his chairmanship on the Senate Judiciary Committee when Republicans take over in January.

If he did step aside, his seat would likely be a safe one for Democrats in liberal Vermont. 

Sen. Barbara MikulskiBarbara Ann MikulskiDems ponder gender politics of 2020 nominee Robert Mueller's forgotten surveillance crime spree Clinton: White House slow-walking Russia sanctions MORE (D-Md.) 

Mikulski, 78, will also be losing a gavel this year.

However, the first woman to chair the Senate Appropriations Committee appears committed to seeking a fifth term. 

She has sought to rally Democrats in Maryland after the party suffered a devastating loss in the race for the governor’s mansion. She is also looking to appoint a party “loyalist” to ease her transition into the 2016 election cycle.

She has less than $900,000 in cash on hand.