Republican Senate candidates hold some sizable cash-on-hand advantages over their Democratic opponents in several key open-seat Senate contests ahead of November. 

Republicans out-raised their Democratic rivals and are sitting on more cash-on-hand in two of the tightest open-seat contests this fall: the race for President Obama's former Senate seat in Illinois and the race to fill the seat of retiring Sen. Jim Bunning (R) in Kentucky.

In Illinois, Rep. Mark KirkMark Steven Kirk The 13 Republicans needed to pass gun-control legislation Advocates push for EpiPens on flights after college student's mid-flight allergic reaction Funding the fight against polio MORE (R) posted another strong fundraising quarter, raising $3.1 million and reporting $4.4 million cash-on-had. His Democratic opponent, Alexi Giannoulias, raised $2.3 million and reported just over $1.1 million on hand. 

In Kentucky, Republican Rand PaulRandal (Rand) Howard PaulRepublicans wary of US action on Iran EXCLUSIVE: Swing-state voters oppose 'surprise' medical bill legislation, Trump pollster warns Rand Paul: Almost every mass shooter 'is sending off signals' MORE out-raised Democrat Jack Conway by $1 million. Paul raised some $2.7 million from July through September to Conway's $1.7 million. The Republican reported $1.4 million cash on hand to just about $1 million for Conway.   

Similarly, in Missouri, New Hampshire, Ohio and Indiana, Republican candidates hold big-cash on-hand leads. 

Rep. Roy BluntRoy Dean BluntGOP group's ad calls on Graham to push for election security: 'Are you still trying?' Exclusive: Kushner tells GOP it needs to unify behind immigration plan The Hill's Morning Report - Can Trump save GOP in North Carolina special election? MORE (R-Mo.) topped Democrat Robin Carnahan's cash-on-hand number by more than $1.5 million in the Show-Me State. 

In New Hampshire, Republican Kelly AyotteKelly Ann AyotteGOP fears Trump backlash in suburbs Trump makes rare trip to Clinton state, hoping to win back New Hampshire Key endorsements: A who's who in early states MORE has close to half a million more in the bank than Rep. Paul Hodes (D-N.H.). 

And in Ohio, former Rep. Rob PortmanRobert (Rob) Jones PortmanCost for last three government shutdowns estimated at billion The Hill's Morning Report - Trump takes 2020 roadshow to New Mexico The 13 Republicans needed to pass gun-control legislation MORE (R) is absolutely trouncing Democrat Lee Fisher. Portman reported more than $6 million on hand at the end of the third quarter while Fisher has less than $400,000 in the bank.  

Former Sen. Dan CoatsDaniel (Dan) Ray CoatsTrump has named more ex-lobbyists to Cabinet in 3 years than Obama, Bush did in full terms: report Hillicon Valley: FCC approves Nexstar-Tribune merger | Top Democrat seeks answers on security of biometric data | 2020 Democrats take on Chinese IP theft | How Google, Facebook probes are testing century-old antitrust laws Congress should defy Dan Coats' last request on phone surveillance MORE (R-Ind.) also has the money edge in Indiana's Senate race, which hasn't appeared competitive for a while. Not only does Coats enjoy a double-digit poll lead, but he's sitting on some $1.3 million, while Rep. Brad Ellsworth (R-Ind.) has less than $900,000 in the bank. 

Another large differential came in a race that has shown no real sign of tightening in recent weeks. In Delaware, Tea Party favorite Christine O'Donnell raised an impressive $3.8 million in the quarter and holds a big cash edge on Democrat Chris CoonsChristopher (Chris) Andrew CoonsBill to return B in unredeemed bonds advances Grassley: Kavanaugh classmate didn't contact Senate panel Democratic senator: Attacks on Saudi oil refineries 'may call for military action against Iran' MORE

Coons raised just $1.5 million and reported $1.3 million cash-on-hand. O'Donnell is sitting on $2.6 million and continuing to raise sizable amounts of cash online, according to her campaign. 

Still, Coons has led O'Donnell by double digits in every poll of the race for the past month. 

One Democrat who didn't fall victim to the open-seat pattern was Rep. Joe Sestak (D-Pa.), who actually reported slightly more cash-on-hand than former Rep. Pat Toomey (R) despite not raising as much as his Republican rival during the third quarter.

Even as Republicans have a cash advantage in most open-seat races, the financial outlook is brighter for some vulnerable Democratic incumbents. In both Wisconsin and California, Democrats outperformed their Republican challengers. 

Sen. Russ Feingold (D-Wis.) raised $4.2 million and has $3.5 million on hand. That easily tops Republican Ron JohnsonRonald (Ron) Harold JohnsonRepublicans wary of US action on Iran Democratic senator warns O'Rourke AR-15 pledge could haunt party for years Conservatives offer stark warning to Trump, GOP on background checks MORE's $3.3 million haul for the third quarter. Johnson reported just $2 million in the bank.

And in California, Sen. Barbara BoxerBarbara Levy BoxerHillicon Valley: Ocasio-Cortez clashes with former Dem senator over gig worker bill | Software engineer indicted over Capital One breach | Lawmakers push Amazon to remove unsafe products Ocasio-Cortez blasts former Dem senator for helping Lyft fight gig worker bill Only four Dem senators have endorsed 2020 candidates MORE (D) hauled in some $6.2 million, which edged Republican Carly Fiorina's $5.8 million. The incumbent also has an enormous cash-on-hand advantage in that race, sitting on $6.5 million to Fiornia's $1.8 million.   

Even though the party has lots of ground to defend, another good sign for Democrats are the numbers from the Democratic Senatorial Campaign Committee, which out-performed its Republican counterpart in September. 

The DSCC raised $15.5 million in September for its largest monthly total ever. The National Republican Senatorial Committee hauled in $8.3 million. 

Democrats also lead when it comes to cash on hand — the DSCC reported $25.6 million to the NRSC's $19.2 million.