A fix for the nation’s spending woes may not have been decided Wednesday afternoon, but in what may be the most consequential clash so far this Congress, vulnerable Senators finally had to start taking sides.

Their votes on Republican and Democratic proposals for spending cuts were being closely watched by both parties’ campaign committees, a host of powerful interest groups and potential challengers.

“Everything is viewed through that prism unfortunately,” said Sen. Olympia Snowe (R-Maine), who faces a potential primary challenge as well as Democrats looking to portray her as moving to the right to appease the tea party. Snowe voted for the House Republican plan cutting $61 billion in spending to make a statement on the need for belt-tightening, she said, even though it includes policy riders and cuts she opposes.

“I’ve always been strong on fiscal issues,” she said, adding that she would have preferred to avoid the partisan standoff and to have the right to offer amendments.

But Wednesday’s vote, according to a Maine Democrat considering challenging Snowe, may have begun to redefine a Republican long-respected by Mainers on the right and left for her moderate positions.

“It might be a redefinition at this stage in the game,” Rosa Scarcelli, a former Maine gubernatorial candidate, said shortly before the vote.

Scarcelli has previously said that her decision to run would be driven in part by whether Snowe shifts dramatically to the right ahead of a primary. She acknowledged that Snowe faces a difficult road no matter how she votes.

“I do think there will be a recognition within her party as to how she votes, and likewise Democrats and independents will be paying close attention,” she said.

Sen. Scott Brown (R-Mass.), who is likewise caught between the tea party and his state’s liberal bent, also backed the GOP plan after keeping mum beforehand, saying in a statement that he doesn’t like many pieces of the House bill but wants to cut the deficit, which the White House projects will hit $1.65 trillion this year.

His vote may help start to repair his strained relations with tea party supporters, said Christen Varley, leader of the Greater Boston Tea Party.

“We love the idea of him being independent, but independence can only go so far to excuse bad votes,” Varley said when Brown’s intentions were unknown just before the vote. “We’re in the hole. We’re broke. There are tough choices to make.”

Tea party criticism of Brown has led to speculation that he could face a primary challenger, but one has yet to emerge. Varley suggested, however, that Massachusetts conservatives hardly felt the heavy lifting was done.

“Let’s be honest here, $60 billion? Come on. It is time for drastic action,” Varley said. “And we’re still not getting it.”

A handful of vulnerable Democratic moderates, meanwhile, bolted from their leadership alternative, which cut about $10 billion, although no Democrat backed the House bill. The Democratic plan garnered just 42 votes, less than the 44 for the House bill, even though Democrats have a 53-47 majority.

Several moderate Democrats up for re-election in 2012, starting with Sen. Joe Manchin (W.Va.) on Tuesday and joined by Sens. Ben Nelson (Neb.) and Claire McCaskill (Mo.) on Wednesday, went to the floor to announce their plans to vote against both parties’ blueprints — talking up the need for cuts but declaring their independence from their own party as well. Other Democrats up in 2012 also voting “no” on the Democratic blueprint included Sens. Herb Kohl (Wis.) and Bill Nelson (Fla.).

“Democrats did nothing to attract Republicans and Republicans did nothing to attract Democrats,” Ben Nelson said. “Now it’s time to get serious.”

He dismissed the idea that Wednesday’s votes amount to much politically. “Who would pay attention to either one of these bills?” he asked. “Neither of them are serious.”

McCaskill said the Democratic Party faces a “gut check” moment on cutting spending and said she doesn’t worry about what the Republican attacks look like. “No matter how I vote, they’re going to go after me,” she said.

Indeed, they did, with the National Republican Senatorial Committee blasting her for opposing the House cuts and a likely Republican challenger using her votes to send out a fundraising appeal.

“If every Missouri family and small business took the same approach to spending and debt that Claire McCaskill takes with spending their tax dollars, every single one of them would be bankrupt and destitute,” said NRSC spokesman Chris Bond.

It was the same on the other side, where the Democratic Senatorial Campaign Committee went after vulnerable Republicans such as Brown.

“We knew that Scott Brown had become a tool of the Republican establishment in Washington but we did not know he’d ever vote against Massachusetts jobs,” DSCC spokesman Eric Schultz said. “It is now official: Scott Brown supports the extremists in his party over the people of Massachusetts. He will be explaining today’s vote for the next 19 months.”

But neither of the campaign committees had paid attack ads planned around the votes — holding their fire for even bigger fights yet to come.

Chris Chocola, president of the Club for Growth, said Wednesday’s votes may have been the most significant of the new Congress, but they were the first of three markers likely to play strongly in 2012. The next will be the vote for the fiscal 2012 federal budget. And “the mother of all battles” will be the vote to raise the nation’s debt ceiling, he added.

The club didn’t plan any paid advertising around Wednesday’s votes, but it will likely run an “issue advocacy” campaign around the debt ceiling debate, according to Chocola.

“I think this is a balancing act,” he said of the political posturing at play Wednesday. “And it won’t be the last act. They’ll have to deal with this for the entire session.”