On the campaign trail, the wonky language of federal financial policy often morphs into something unrecognizable to its fluent speakers.

Far from Washington, Main Street is good. Wall Street and bailouts are bad. Bonuses for bailed-out executives are worse.

An epicenter of such populist rhetoric this year is Montana, where Democratic Sen. Jon Tester, a member of the Senate Banking Committee, is locked in a tight reelection race against Republican Rep. Denny Rehberg. The two candidates are warring over bailouts, bonuses and the role of campaign money from the financial sector. On both sides, anti-elitism reigns.

"A lot of Montanans were skeptical of the bailouts, so it's easy to use these very complicated issues in a very simplistic way," said David Parker, a political science professor at Montana State University.

Among the campaign issues is Tester's high-profile stand on interchange fees. Last year, he sponsored a contentious bill — supported by the banking industry — to delay limits on debit-card swipe fees. Rehberg has charged the bill shows Tester in the industry's pocket. In return, Tester has argued that Rehberg is out of step with Montana voters.

The Montana campaign is getting a lot of national attention because it is one of several races that will determine whether the Senate swings into Republican hands. Outside groups on both sides are spending so much money that they are swamping the candidates' own expenditures. Polls show the race is extremely close, and analysts currently rate it as a toss-up.

Although financial policy is not the most important issue in the Montana campaign — the economy, health care and land-use policy are all near the top of the list — it is being used by both sides to raise questions about the independence of their opponent.

At a June 16 debate, Rehberg accused Tester of being unduly influenced by Wall Street, pointing to the interchange bill. Tester's legislation against a cap on debit-card interchange fees was one of the financial industry's top legislative priorities of the last two years.

Referring to Tester's opposition to curbs on outside spending in the campaign, Rehberg asked: "Why? Probably because of the payoff from the swipe fee … and all the Wall Street money that came in as a result of his decision to carry that legislation."

"That was the payoff," Rehberg said. "He even admitted in the press that it was money that probably came in as a result of carrying that legislation. That's what's wrong with our political system."

But at the same debate, Tester turned the charge around on Rehberg. He implied it was the six-term GOP congressman who lacked independence as demonstrated by his vote against the Dodd-Frank Act.

"It held Wall Street accountable," Tester said of the bill, which was opposed by much of the financial industry as well as by nearly every congressional Republican, before adding:  "But he opposed it, for obvious reasons."

Campaign finance records show that Tester's campaign and his political action committee have raised more than $1.6 million from the financial, insurance and real estate sector in the current election cycle, while Rehberg has raised about $570,000 from the sector.

Those figures do not account for money from lobbyists, or spending by outside organizations such as the Electronic Payments Coalition. The payments group, which opposed the interchange cap, has run ads in support of Tester. Meanwhile, outside conservative groups, some of which have not disclosed the sources of their funding, are supporting Rehberg.

But despite the financial industry's significant role in the race, the two candidates are both attempting to cast themselves as the one true opponent of bailouts.

Tester, for example, has highlighted the fact that he was one of few Democrats to vote against the bill creating the Troubled Asset Relief Program. (Rehberg also opposed Tarp.)

"I'm in this job not because I'm known as a guy who stands up for big banks and Wall Street," Tester said in a speech on the Senate floor last year. "I'm the guy in my party who voted against Tarp and against the automaker bailout."

More recently, Tester has argued that he also opposed the "Greece bailout," pointing to a 2011 vote where he was the only Senate Democrat who favored repealing a U.S. line of credit to the International Monetary Fund.

But Rehberg is still trying to label Tester as a supporter of Wall Street and bailouts. He condemned Tester for his vote in favor of the Housing and Economic Recovery Act of 2008. But Rehberg's claims that "Senator Tester voted to spend $300 billion to bail out Fannie Mae and Freddie Mac at taxpayer expense" is misleading.

The housing law, which passed the Senate 72-13 with significant Republican support, established the framework for the government's eventual conservatorship of Fannie and Freddie. But no credible observer believes that the law was necessary for a government bailout of the two housing giants, or that a bailout would not have happened had the law not been in place.

Pat Williams, a former Democratic congressman from Montana, said that none of the 2008 bailouts were popular in the state, but they became even less so after executives at bailed-out financial institutions such as American International Group received large bonuses.

"It was at that point that the objection became very loud," said Williams, who now teaches at the University of Montana. "And politically, that's a pretty hard argument to stand against in Montana."

That dynamic explains why the Montana Democratic Party has been running ads accusing Rehberg of voting to give Wall Street CEOs bonuses funded by taxpayer bailouts, and Rehberg has lobbied the same charge back at Tester.

Despite the fact that both campaigns are lobbing the same charges at each other, there are real ideological differences between the two candidates.

Rehberg, who represents the only congressional district in the whole state, has aligned himself with the Tea Party movement. He brought Rep. Michele Bachmann, R-Minn., to Helena for his campaign announcement, and has repented for his past support of earmarks.

Tester, on the other hand, has been a fairly reliable vote in support of President Obama's agenda. He voted for the 2009 stimulus, health-care reform and Dodd-Frank, though today he is eager to point out instances where he and the president have disagreed.

But on most financial policy issues, the two candidates are striking similar poses. Both want to be seen as allies of the little guy.

At last month's debate, Tester argued that his push to delay debit interchange caps "had to do with saving our community banks and credit unions in the United States."

Tester also said that he has been using his seat on the Senate Banking Committee to work with industry regulators "to make sure that they treat our community banks fairly, so they can get the money out the door."

Rehberg made a similar argument about the threats facing community banks, though he blamed Dodd-Frank.

"The people who are struggling right now are the Montana community bankers. And to a banker, you talk to them about the regulations that are being brought down on them by Dodd-Frank, they are in opposition. They're afraid. They can't move, and they get whipsawed," he said.

In the end, the election may turn on which candidate voters see as more authentically representative of Main Street.

That may be why Tester returns home to work on his farm nearly every weekend, and why Rehberg is arguing that the Democratic incumbent presents one face in Montana and another in Washington.

Given the importance of authenticity to Montana voters, some observers believe that the flood of money from out-of-state groups could backfire.

"People in most of the Rocky Mountain states are fairly provincial," Williams said. "They're bound to the region and to the locality. And thus outside political spending — telling them why their favorite politician or the opposition is a no-good SOB — really turns voters out this way completely off."

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