Updated

Maryland Republican Rep. Roscoe Bartlett won Tuesday's primary, allowing him to seek an 11th term in one of the most closely watched House races this year.

Bartlett edged out state Sen. David Brinkley and delegate Kathy Afzali in a wide-open race where the 85-year-old congressman faced off challenges from Democrats and Republicans.

Maryland Democrats targeted Bartlett for defeat last year by redrawing his largely conservative Western Maryland district to include parts of the more liberal Montgomery County.

They also hand-picked state Senate Majority Leader Rob Garagiola as a candidate. However, Garagiola was defeated Tuesday by Democrat Joe Delaney, a Montgomery County businessman and founder of commercial lender CapitalSource Inc.

Delaney had endorsements from Maryland Rep. Donna Edwards and former President Bill Clinton. He also poured nearly $1.4 million of his own money into his campaign and far out-raised and out-spent Garagiola.

Garagiola had the backing of Maryland Gov. Martin O'Malley and Democratic Reps. Elijah Cummings, Dutch Ruppersberger and Steny Hoyer.

Bartlett defeated a total seven primary challengers to avoid becoming the third House Republican to lose in the 2012 primaries.

Political observers expected the challengers to split the anti-incumbent vote, allowing Bartlett to win.

Bartlett also significantly outspent his opponents. He reported raising $218,000 between January 1 and March 14. Brinkley raised $21,000 and Afzali raised $20,000 over the same period.

In other Maryland races, five Democratic congressional members were nominated for re-election as expected in the Tuesday primaries.

Democratic voters nominated John Sarbanes in the 3rd Congressional District, Donna Edwards in the 4th, Steny Hoyer in the 5th, Elijah Cummings in the 7th and Chris Van Hollen in the 8th.

Their Republican opponents in the November general election were in races too close to call.

The state's two other House members were uncontested in the primary. They are freshman Republican Rep. Andy Harris in the 1st District and Democrat C.A. Dutch Ruppersberger in the 2nd.

Bartlett's 6th District, in western Maryland and a longtime GOP stronghold, was drastically reshaped by Democratic-led redistricting to make it competitive for the first time since Bartlett won it in 1992.

The prospect of a close November contest, or even a primary defeat, energized the congressman's campaign. He planned to shake hands in five locations Tuesday, including two in Washington County.

Republican Ron Frost, a retired IBM inventory-control specialist from Hagerstown, said he cast his vote for Bartlett in the 6th Congressional District race partly because he believes he is honest.

"I felt like he was telling me the truth more than the other people were," Frost said. "There have been some things said about him that I know are lies. Once a person lies to me about something, I can't trust them after that."

Republican Evelyn Edwards, 86, a retired housewife from Urbana, said she also voted for Bartlett.

"He's an elderly man but he's been around long enough to know what's going on," she said.

Brinkley claims Bartlett hasn't lived up to his conservative talking points, citing his August vote in favor of raising the U.S. debt limit by $2.1 trillion in exchange for an equivalent amount in spending cuts.

Bartlett says he voted for what he called "a very bad bill" to avoid a default on U.S. debt obligations. The congressman says his critics don't understand the complexity of bills that sometimes require him to cast votes that apparently contradict his views.

Their generally civil contest turned nasty Saturday when a group called Victory for Bartlett emailed to the district's registered Republicans clips of 911 police recordings from a 2008 domestic disturbance between Brinkley and his wife, who have since divorced.

Brinkley's campaign called the email "a pathetic act of desperation." Bartlett's camp denied any role in the tactic.

Bartlett also got a plug Monday from Republican presidential candidate Newt Gingrich.

Gingrich, speaking in Frederick, praised Bartlett for bringing attention to the threat of electromagnetic pulse weapons that an enemy could use to cripple America's electrical network by detonating a large explosion in space.

Garagiola started the race as the perceived favorite since the redrawn district includes a large chunk of heavily Democratic Montgomery County where he lives.

In an exchange of attacks, Delaney painted Garagiola as an opportunistic political climber in league with the Washington lobbyists for whom Garagiola once worked and who also backed the state senator's candidacy.

Garagiola countered by calling Delaney a "loan shark" whose company preyed on working families during the recession.

Fox News' Chad Pergram and The Associated Press contributed to this report.