Delaney also received an early endorsement from former Montgomery County Executive Doug Duncan, who said he backed Delaney because he was "very upset at how our Annapolis leaders basically handpicked our congressional candidate and … said, 'take him.'"
Unlike Garagiola, Delaney's fundraising and personal wealth allowed him to blanket cable television and radio with ads promoting his business credentials and attacking Garagiola. As head of a Chevy Chase-based bank called CapitalSource, Delaney had the means to cut his campaign a $359,000 check in the final days of the race, Federal Election Commission reports show.
Aside from a radio ad paid for by the Service Employees International Union, Garagiola never went on the air.
Two candidates in the 1st Congressional District, John LaFerla of Chestertown and Wendy Rosen of Cockeysville, both ran aggressive campaigns for the Democratic nomination. Rosen claimed victory in the race late Tuesday, but the race was close and LaFerla had not conceded. The district, which includes the Eastern Shore and Baltimore's northern suburbs, is considered safe territory for Harris, the Republican incumbent.
Harris did not face a primary challenge.
State Sen. Nancy Jacobs, meanwhile, fended off several candidates seeking the Republican nomination in the 2nd District. The seat is currently held by Democratic Rep. C.A. Dutch Ruppersberger, who had no opposition in the primary.
The majority of the fireworks in Maryland played out in the 6th District.
Delaney relentlessly attacked Garagiola's work as a federal lobbyist for a powerful Washington firm that also employed Jack Abramoff, who pleaded guilty to providing gifts to elected officials. Delaney's campaign pointed out that Garagiola had failed to note his work for the firm on state disclosure forms from 2001 to 2003.
Garagiola's aides, meanwhile, scoured through Securities and Exchange Commission filings from Delaney's bank, noting that the company was being audited by the IRS and had a stake in other companies that bought tax liens and foreclosed on hundreds of homes. Garagiola also noted that Delaney, a prolific Democratic fundraiser, had given a $2,400 contribution to the Harris campaign in 2010.
The landscape was different on the Republican side. Initial speculation that Bartlett, who is 85, would retire rather than run a challenging reelection effort was laid to rest in January when he began fundraising and hired a well-known California-based political consultant to help run his campaign.
Several high-profile contenders, including state Republican Party Chairman Alex X. Mooney, ultimately abandoned potential challenges to clear the way for Bartlett.
That left two state lawmakers in the hunt for the Republican nomination, state Sen. David R. Brinkley and Del. Kathy Afzali, as well as a handful of businessmen, including Brandon Rippeon and Joseph Krysztoforski. Brinkley, Afzali and Krysztoforski all live outside the district. The two state legislators were hamstrung by the legislative session, which kept them in Annapolis rather than on the campaign trail. And none of them came close to Bartlett's fundraising.
Nancy Zachik's decision to vote for Bartlett underscored the advantage, and loyalty, that often help propel incumbents to victory in elections.
"I'm not going to be responsible for him leaving," said Nancy Zachik, a 55-year-old Rockville resident. "He's one of the only ones in Washington who votes like I would."
Baltimore Sun reporters Yvonne Wenger, Kevin Rector and Alison Knezevich contributed to this article.