Wave of Top Republicans Rally Around Sen. Pat Roberts

— -- Kansas has become the destination for the Republican Party's biggest names as they swarm to the state to bolster the reelection bid of Sen. Pat Roberts, whose seat could make the difference in the GOP's hope to win control of the Senate.

Former Gov. Jeb Bush is heading to the state to campaign next Monday, aides said. Sen. Rand Paul, R-Ky., and Rep. Paul Ryan, R-Wis., are also coming next month to try and rescue 78-year-old Roberts.

These newest additions accompany a list of three former presidential candidates -- who all lost -- already giving a hand to the campaign.

Former Massachusetts governor and presidential candidate Mitt Romney recorded a robocall that ran throughout the state two weeks ago. Former Kansas senator and another GOP presidential candidate Bob Dole is back in the state this week attending town halls with Roberts. Roberts will then be joined by John McCain, the Arizona senator who also lost a presidential run, at campaign events Wednesday and Thursday.

McCain’s running mate former Alaska governor Sarah Palin is also rumored to be a “special guest” at a pancake breakfast in Independence, Kan., on Wednesday morning, according to the Wichita Eagle.

Ryan, Paul and Bush have all generated buzz over their potential as contenders for a spot on the Republican presidential ticket in 2016.

Now, they are working the state to help defeat Independent candidate Greg Orman. The multimillionaire businessman has shown a lead over Roberts in several recent polls, and with Democrat Chad Taylor now off the state’s ballots, Republicans are more jittery over the prospect of Orman defeating Roberts -- and being a deciding factor in the balance of the Senate.

Kansas Democratic Party Chairwoman Joan Wagnon told ABC News her group has no plans to endorse Orman, but they are in full support of Kansas voters voting out Roberts.

“The fact they have to prop [Roberts] up with all of this star power shows a lot about their concerns about this race,” Wagnon said. “They’re trying to nationalize this election and I think they’ll find out that Kansans really don’t like that.”

Republicans have been quick to paint Orman, 45, as a liberal, though he has not yet indicated which party he would caucus with if he is elected.

In a video posted to his campaign website, Orman says, “If I get elected to the United States Senate, there’s a reasonable chance that neither party will have a majority. And if that happens, that’s a great thing for Kansas.”

“Those senators who are centrist like myself… would be able to come together and basically say we are going to caucus with whichever party is willing to solve our country’s problems,” Orman says. “It’s something we’ve never really seen before in the United States Senate. We’ve never really seen the opportunity to hold the party in charge responsible.”

Roberts' campaign manager Corry Bliss said the outside help was an indication of the importance of the election.

“The Republican Party is uniting around Pat Roberts because he is the only candidate in this race who will ensure Harry Reid is no longer in control of the Senate,” Bliss said in a statement to ABC News.

Orman registered to run as a Democrat in 2008 and voted for Barack Obama that year, but he also has said he voted for Romney and Ryan in the 2012 election, both of whom are now campaigning against him.

Paul and McCain are the only sitting U.S. senators to commit to campaign in the state for Roberts, but could also be potential colleagues to Orman if he defeats Roberts in November.

Orman’s campaign did not respond to a request for comment.