The Biggest Winners in Senate Budget Votes? Political Operatives.

A cascade of amendments won't affect policy, but they'll be part of 2016 political campaigns.

Senators casting votes on an unending stream of amendments to the budget resolution this week won't be writing any new laws. But they will—deliberately or not—be helping write some campaign ads.

The Senate kicked off its budget "vote-a-rama" at noon Thursday, with roughly 12 hours of non-stop tallies on tap. Members' decisions on scores of amendments to the nonbinding budget blueprint will help political operatives in both parties craft a stream of commercials, press releases, and fundraising appeals. And that means the budget process could matter for politically vulnerable members facing reelection in 2016 as well as the GOP's presidential contenders.

Already, both parties are hunting for ammunition among votes that have started on topics such as wages, environmental regulations, and Medicare.

"A lot of the Democrat amendments are really messaging amendments," said Republican Sen. John Thune. "They will try and get our guys to take votes that the Democrats think are going to put them in difficult political situations in 2016. "¦ But that's the budget process here, and like [Senate Majority Leader Mitch] McConnell has always said, if you don't want to make hard votes, don't run for the Senate."

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The Democratic Senatorial Campaign Committee has been blasting Pennsylvania Republican Pat Toomey, who is up for reelection next year, for pushing through an amendment in the Budget Committee last week that Democrats call an effort to weaken the Consumer Financial Protection Bureau.

"A budget isn't just numbers on a page—it's a moral document. Senate Republicans like to talk one way at home and vote another in Washington, but we'll be ready to hold them accountable as their budget and the amendment process reveals their dangerous priorities for women, seniors, and the middle class," said Ben Ray, a spokesman for American Bridge 21st Century, a Democratic super-PAC.

But Republicans are similarly looking for opportunities to force Democrats to cast tough votes. Sen. Roy Blunt, for example, is again seeking to put colleagues on record on carbon taxes.

And while it's not clear which of the hundreds of amendments filed will receive votes, the roll call marathon could give presidential contenders a chance to get noticed. Florida Republican Marco Rubio, who is moving toward a White House run, has one amendment aimed at "ensuring that Medicare is not raided to bailout insurance companies under the President's health care overhaul," and another amendment to boost defense spending. Another presidential hopeful, Sen. Rand Paul, also has an amendment to devote billions more to the Pentagon.

It's no coincidence that swing-state members facing voters in 2016 have quickly moved to the forefront of the budget fight.

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On Wednesday the Senate, in a largely party-line vote, rejected Colorado Democrat Michael Bennet's amendment attacking any effort to privatize Medicare or cut guaranteed benefits.

The potential usefulness of the budget fight in boosting 2016 members is not lost on GOP leadership either.

At his weekly press conference Tuesday, Senate Majority Leader Mitch McConnell introduced "some members of the Budget Committee"—they just happened to be three of the most vulnerable Republicans facing reelection next year: Sens. Kelly Ayotte of New Hampshire, Ron Johnson of Wisconsin, and Rob Portman of Ohio. Each used the opportunity to reinforce strengths they'll be trotting out on the campaign trail over the next year.

Ayotte, a purple-state defense hawk, discussed her efforts to increase funding for the Pentagon and noted her willingness to work with Democrats on the issue. Johnson, a conservative who has made his willingness to tell uncomfortable truths central to his reelection message, talked about getting into an argument with President Obama at the White House last year over whether or not to make the nation's staggering debt figures clear to the public. And Portman, a former director of the Office of Management and Budget under George W. Bush, highlighted the two parties' very different visions for the nation's fiscal future.

Portman said Wednesday he wasn't worried about the amendments Democrats might throw at him and other Republicans up for reelection this cycle.

"We'll just do the right thing," Portman said. "I'm not concerned about the number of amendments and healthy debate. I think it's a good thing. And you know we'll have issues to deal with climate change and economic growth and we'll have the opportunity on the budget to get our points of view across."

This article has been updated.