Republicans are facing yet another competitive Senate primary, which could undermine the GOP's plan to retake control of the upper chamber next year.

New Mexico Lt. Gov. John Sanchez made his candidacy official Tuesday, announcing his intention to succeed retiring Sen. Jeff Bingaman (D-N.M.). Perhaps foreshadowing what's to come, Sanchez opened with a thinly disguised jab at his main rival for the GOP nomination, former Rep. Heather Wilson (R-N.M.).

"In Washington, many good people have lost their way by choosing what is easy instead of what is right, by raising taxes and bailing out big companies and banks, by compromising values for short term political gains and by slowly giving away a little of who they are for a little of what they want," Sanchez said in a statement. 

Republicans, who are defending 10 seats this cycle, need a net gain of four (if President Obama wins reelection) to take control of the Senate. Democrats, meanwhile, are faced with the task of defending 23 seats.

But one point of optimism for Democrats is that there are competitive primaries in several states where they have vulnerable incumbents. Missouri, Florida and Nebraska all have competitive GOP races for their Senate nominations. 

In New Mexico, Sanchez has twice run statewide, losing the gubernatorial race to Democrat Bill Richardson in 2002 before capturing the state's No. 2 job last November.

Sanchez's decision to pursue another office only months after assuming his current position could be a liability. His opponents could use it to portray him as a political climber and the responsibilities of the job could keep him off the campaign trail. Sanchez, who also owns a roofing company, brushed off the suggestion his official duties could handicap his campaign.

"Not at all," he said in an interview. "After today we look forward to getting on a statewide announcement tour. We look forward to spending quite a bit of windshield time across New Mexico."

Meanwhile, he has an announcement TV ad airing statewide on cable and broadcast TV.  

During a trip to Washington in March, he showed no reluctance to criticize Wilson.

"I think Heather served honorably," he told The Ballot Box. "But if we consider the choices that were made by former establishment candidates, I think it's clear the choices will be very easy for the people of New Mexico.

"Do they want a return back to the days of moderate-type leaders [whose] conservative compasses [weren’t] pointed in the right direction? Or are they looking for somebody who doesn't have to reinvent himself?" he said. "I think the choice for U.S. Senate is abundantly clear." 

In addition to Sanchez and Wilson, businessman and former congressional candidate Greg Sowards and Bill English are also in the hunt for the GOP nod.

In a statement, the Wilson camp said the congresswoman looked forward to contrasting her "conservative record with his invented one."

"On issue after issue John Sanchez is not who he says he is, and Republican voters will be quick to figure that out," her campaign said.

Sowards called him a "moderate."

"Sanchez will now try to paint himself as a conservative, hoping that Republican voters will see past his moderate voting record and a career full of unfulfilled political promises," Sowards said in a statement.

Meanwhile, Democrats are expected to nominate Rep. Martin HeinrichMartin Trevor HeinrichHillicon Valley: Sweeping new data rules take effect | Facebook, Google already hit with complaints | Schumer slams reported ZTE deal | Senators look to save cyber post | Dem wants answers about Trump's phone security Senators express concern over Trump's decision to scrap top cyber post Hillicon Valley: AT&T calls hiring Cohen a 'big mistake' | Wyden wants to block DHS nominee over Stingray surveillance | Amazon pressed on child privacy | One year anniversary of Trump cyber order MORE (N.M.), who announced in March that he will run for the Senate seat being vacated by Bingaman. But he faces state Auditor Hector Balderas in a primary that his rivals have characterized as a race between a Washington insider and two grass-roots candidates. Political activist Andres Valdez, who leads the community group Vecinos United, is also running.

Heinrich, who represents New Mexico's 1st Congressional District, is in his second term in the House.

--Updated at 4:43 p.m.