The stakes, and the unpleasantness, are highest in the race for control of the Senate, where Republicans need to gain four seats to win the majority—only three if Republican Paul Ryan becomes vice president and, in his role as Senate president, breaks any tie votes.
In Massachusetts, GOP Sen. Scott Brown witheringly mocks Democrat Elizabeth Warren's claims of Native American heritage. In Montana, Democratic Sen. Jon Tester pummels Rep. Denny Rehberg for suing a local fire department. Nevada's Sen. Dean Heller calls his opponent, Democratic Rep. Shelly Berkley, "the most corrupt" person he's ever met.
Across the land, candidates are launching incendiary attacks on each other in the final, fretful days of an election year colored by margin-of-error races that have refused to budge.
In the battle for control of the Senate, neither Republicans nor Democrats have put away enough seats to tip the balance of power. Republicans are favored to hold onto the House, where Democrats need to net 25 seats to regain control, but both parties want to win as many seats as possible.
Many candidates have maximized the support they can get by selling their own records and accomplishments and are now going negative, seeking to damage an opponent's credentials and depress his or her support. That point arrived long ago in the presidential contest. Down-ballot, things seem to just now be coming to a boil.
The closer the contest, the harsher the attacks.
Take Montana, home to one of the nation's closest and most bitter Senate races.
Sniping between Tester and Rehberg over who's the real Montanan and who's beholden to lobbyists turned harsher in the past week after Democrats launched a trio of ads searing Rehberg for suing a local fire company for damage on his land during a blaze. Tester personally took the matter to Rehberg in a face-to-face debate this week.
Firefighters "put their butt on the line. You don't turn around and respond by filing a lawsuit with monetary damages," Tester told Rehberg. "That is what you did."
Rehberg shot back with an accusation that Tester values his party over his state.
"No one has brought up the fire lawsuit, except for you," Rehberg said. "You know what (voters) talk about? The irresponsible decisions of supporting President Obama 95 percent of the time."
Nevada's Heller has pounded Berkley for being the subject of a House Ethics Committee investigation into whether she used her office to push policies that benefited her husband's medical practice. Berkley has been no less harsh. One of her recent ads highlighted Heller's past friendship with a man later convicted of money laundering.
"Eddie Floyd, a crooked businessman who pled guilty to laundering drug money—a friend of Dean Heller's," the narrator says in one recent ad being run by Berkley's campaign.
Republicans in Connecticut have been buoyed by the better-than-expected performance of former wrestling executive Linda McMahon in her contest with Rep. Chris Murphy to replace retiring Sen. Joe Lieberman. The candidates have criticized each other in starkly personal terms.
In a recent ad, McMahon—countering a Murphy attack accusing her of wanting to make changes to Social Security and Medicare—suggested he is a liar.
"Murphy didn't tell us the truth about when he was sued in court for not paying his rent, sued for not paying his mortgage, or missing 80 percent of his committee hearings," says a narrator in the ad. "So do you think Murphy is telling the truth now?"
In House contests, some of the harshest ads are being cooked up by the parties' campaign arms.
The House Democrats' campaign committee has run an ad against Rep. Bobby Schilling, R-Ill., featuring voters pointedly asking "Bobby" why he abandoned them. Another of the Democratic committee's ads features a nurse in hospital scrubs talking to the camera about Nevada GOP Rep. Joe Heck's opposition to the HPV vaccination, which aims to stop the cancer-causing virus. She accuses Heck of being "against saving lives."
The Republicans' House campaign committee, in an Internet ad and mailings, links the Democratic challenger in a Pennsylvania race, Kathy Boockvar, with a man convicted of killing a police officer in 1981. Boockvar is challenging Rep. Mike Fitzpatrick, R-Pa. Her husband, a lawyer, represented a witness in the case who later recanted her testimony.
Another GOP committee spot, more playful but still personal, slams Rep. Dave Loebsack, D-Iowa, for dozing off at a meeting on Obama's health care overhaul.
Perhaps the most persistently testy down-ballot contest in the country has been in Massachusetts, where Brown and Warren have shown a clear disdain for each other in two televised debates and a slew of ads.
Brown set the tone early: Near the outset of the candidates' first debate, he criticized Warren for claiming Native American heritage. His opponent "checked the box claiming she is Native American, and clearly she is not," he said. Warren, seeming slightly galled, said her parents told her growing up that her mother was of Native American heritage.
Brown seemed to acknowledge the attack had gotten out of hand when he released a statement condemning staffers who were caught on video doing a "tomahawk chop" and shouting war whoops designed to mock Warren as Brown spoke at a campaign rally.
Warren has mocked Brown for posing nude in Cosmopolitan magazine to pay for law school. More recently, she accused Brown—a married father of two daughters—of being insufficiently committed to women's issues.
"Women need someone they can depend on, not some of the time, but all of the time," she said in one debate.
Brown snapped back, "You should stop scaring women."