Republican Rep. Vern Buchanan is fighting off a congressional ethics investigation linked to a former business partner and campaign donations. Democratic Rep. Maxine Waters is battling a charge of impropriety about work she might have done to benefit her husband.

They are among nearly a dozen lawmakers seeking re-election while caught up in federal or congressional investigations that are perfect fodder for campaign foes, rival political committees and free-spending outside groups.

But unlike the headline-grabbing, sex-driven Internet scandals of the past year and a half, these probes center on more complicated financial dealings. Roughly five months to the Nov. 6 elections, they pose less of a threat to political careers, especially for deep-pocketed incumbents or lawmakers in districts that are barely competitive.

Last year, in the political equivalent of a New York minute, Democrat Anthony Weiner and Republican Chris Lee quit the House after explicit photos hit Twitter and the Web. Buchanan, Waters and several other lawmakers who are the subject of House ethics committee probes defiantly remain in Congress, insisting they did nothing wrong as they push ahead with their campaigns. Most are favored to win on Election Day.

"I think you have to be found guilty to have it really make an impact," said Bob Edgar, the president and CEO of the good-government group Common Cause and a former Pennsylvania congressman.

And even that won't unseat some lawmakers.

In 2010, the House censured _ the most serious congressional penalty short of expulsion _ Democratic Rep. Charles Rangel of New York for 11 ethics violations, including failure to pay some taxes and using congressional resources to raise money for an academic center bearing his name. Yet he easily won re-election, and is favored to win again in November if he survives the June 26 Democratic primary where a reshaped district, a popular challenger and his age pose a greater threat to the 82-year-old congressman's bid for a 22nd term.

In a campaign season dominated by voters' fears about the economy, ethics isn't drawing the same attention it sometimes does. The slow pace of the investigations also is a factor; the Waters probe has dragged on for almost three years.

"Ethics seems to resonate much more when the economy is less of an issue," said Melanie Sloan, executive director of Citizens for Responsibility and Ethics in Washington, a government watchdog group. "The economy pretty much trumps everything."

Still, that hasn't stopped rivals from trying making ethics an issue.

The IRS and the FBI are investigating whether Republican Rep. David Rivera of Florida filed false tax returns or evaded taxes, a probe that continues after state prosecutors in April ended their yearlong investigation into the congressman's finances without filing charges.

Rivera's campaign dismissed the inquiry as a fishing expedition and said that at all times he acted "in compliance with both the letter and spirit of Florida and federal campaign finance laws and has timely and properly reported all personal income,"

Democrat Joe Garcia seized on Rivera's ethical issues in a video announcing his bid to unseat the Republican.

"Our community is being neglected because our congressman is busier working on his legal defense and covering up his lies than serving his constituents," Garcia said. "We can't sit by on the sidelines and watch this happen any longer. We will work hard to serve you with integrity and honesty."

Although the district now counts more Democratic voters after redistricting, challengers to Rivera have come and gone, handicapping the party's effort to oust him. State Rep. Luis Garcia dropped his bid in April, complaining about heavy-handed tactics by national Democrats. Businesswoman Gloria Romero Roses entered the race and now Joe Garcia, no relation to Luis, is looking to unseat Rivera in a rematch after losing to him 52-43 percent in 2010.

Buchanan, who heads national fundraising for House Republicans, is the subject of a congressional ethics investigation and Justice Department probe into whether he tried to get a former business partner to lie to the government about illegal campaign donations.

A recent congressional report presented evidence that Buchanan, who owns several auto dealerships in Florida, tried to persuade ex-partner Sam Kazran to deny he was aware of reimbursements made to Buchanan contributors. Buchanan's lawyers rejected the report, saying, "from start to finish, the report's conclusions are fundamentally flawed," misstating evidence and concealing exculpatory evidence.

Buchanan is seeking a fourth-term in a slightly more Democratic district. He has a significant cash-on-hand advantage over Democratic state Rep. Keith Fitzgerald, $1.4 million to $422,360, and recently reserved $4 million in television ad time this fall. Democrats have made the race one of their top targets.

"I think it's upsetting how much (Speaker John) Boehner has said, `I will not tolerate ethical misconduct,' but what he's really meant is sexual misconduct," Sloan said, citing the case of former Republican Rep. Mark Souder who resigned in 2010 after admitting to an extramarital affair.

In Nevada, Democratic Rep. Shelley Berkley is pursuing the Senate seat held by Republican Dean Heller, who was appointed to it last year when John Ensign resigned after lying about his affair with an aide's wife.

The House ethics committee is looking into Republican allegations that Berkley tried to use her office to help her husband's medical practice. The Nevada GOP contends that Berkley tried to influence federal reimbursement rates for dialysis providers and lobbied to save a kidney transplant program in Las Vegas to help her husband, Dr. Larry Lehrner, who administers kidney care at University Medical Center in Las Vegas.

The committee will decide on or before July 9 whether to conduct a full investigation. American Crossroads, a group formed by prominent Republican strategist Karl Rove, jumped the gun this week with a tough ad on Nevada television.

"Charged with using her office to enrich her family, Berkley twisted arms to get federal dollars for her husband's business. A blatant conflict of interest. Shelley Berkley makes the system work _ for herself," the commercial says.

Berkley disputes the ad's claims and has sought to turn it to her advantage, citing it in a fundraising appeal.

"I just wanted to make sure you've seen the news about the newest Crossroads attack running against me in Nevada," she said in Thursday's appeal. "Karl Rove sees the same polls we do _ he knows this race will go down to the wire. And he's hoping that attack ads will help tip the scales in his favor. But I have something he doesn't have: a powerful network of grass-roots supporters like you. Only you can give us the resources to respond to the relentless smears."