If Republicans win a Senate majority in the Nov. 4 elections, the party's new governing responsibilities may force potential 2016 presidential candidates such as Marco Rubio of Florida and Ted Cruz of Texas to take uncomfortable votes that open them to criticism from rivals outside of Congress.
While they would have the opportunity to pass legislation on projects such as the Keystone XL pipeline that are important to conservative voters, a thin Senate majority could hamper their ability to deliver on big promises to shrink government and cut federal debt.
That would open the door for rivals who are current or former state governors to campaign against Washington and its unpopular lawmakers, including the Republicans in charge of the House of Representatives and the Senate.
"Anybody who's a senator who's running for president is obviously always in jeopardy for votes they have to cast. It is an advantage that governors have over them," said Republican strategist Charlie Black, an adviser to former Massachusetts Governor Mitt Romney and Arizona Senator John McCain during their presidential campaigns.
Some governors with an eye on 2016 are already looking to exploit their edge over senators.
"I am convinced that the next president of the United States is going to be a governor," New Jersey Governor Christie, a likely 2016 contender, said at the Chamber of Commerce in Washington last week.
"We have had the experiment of a legislator who’d never run anything getting on-the-job training," he said, knocking President Barack Obama, a former senator from Illinois.
Governor Rick Perry of Texas, another likely 2016 contender, is quick to highlight his state's economic successes and his role as the state's chief executive in delivering them. If they start their own campaigns, others like former Florida Governor Jeb Bush and Louisiana Governor Bobby Jindal would no doubt do the same.
But Black and other Republicans said Senate control also could help potential 2016 candidates Cruz, Rubio, Rob Portman of Ohio and Rand Paul of Kentucky by giving them frequent opportunities to shine.
"I think it's all positive," Paul told Reuters in an interview.
'WE'LL START PASSING LEGISLATION'
"I think if we take over the Senate ... we'll actually start passing legislation," Paul said. "There were 400 bills passed in the House last year and not one of them was taken up in the Senate."
That could lead to potentially tough votes on contentious issues such as raising the debt ceiling, keeping the federal government open, reforming the tax code and confirming potential presidential Cabinet or Supreme Court appointments.
It also could give the party's senators a chance to show they can govern responsibly and compromise when needed, Portman said.
"If Republicans are seen as taking the lead on that, in passing legislation, I think it helps," he said in an interview. "If we get a majority Senate, there's a chance that you could get the president to the table, though Republicans would have to do their part in doing that."
Cruz, a hero of the conservative Tea Party who championed last year's government shutdown, has tried to put blame on Democrats in advance if a Republican-ruled Senate is unable to pass legislation. He wrote in a recent USA Today opinion piece that Republicans would pass bills in 2015 or "expose an obstructionist" president.
"We will either pass a serious agenda to address the real priorities of the American people - protecting our constitutional rights and pulling us back from the fiscal and economic cliff - or the Democrats will filibuster or veto these bills," Cruz wrote. "If they do so, we will have transparency and accountability for the very next election."
But Democrats said if Republicans control both houses of Congress it will make it tough for the party's presidential hopefuls to sidestep blame for Washington's ills.
"Senators in that group will have a particular hurdle to try to clear with their own level of responsibility for what’s happening or not happening in Congress," said Michael Feldman, a former adviser to Vice President Al Gore.
"It’s also harder to run from 'outside Washington' if someone’s fulltime job is in Washington," he said. "Governors have an easier time making those arguments."