Buoyed by favorable districts and the power of incumbency, most members of Maryland's heavily Democratic congressional delegation easily won re-election Tuesday, despite a strong national current that favored the GOP.
But in the state's westernmost congressional district, Democratic Rep. John Delaney — a first-term incumbent — faced a spirited challenge from Republican Dan Bongino, a former Secret Service agent who gained prominence two years ago during an unsuccessful campaign for the Senate.
Bongino led in early returns for much of the evening, but several precincts in Democrat-heavy Montgomery County that reported Wednesday morning appeared to give Delaney the lead.
"While not all the precincts are accounted for yet the only remaining precincts…are in Montgomery County," Delaney told supporters Wednesday from Gaithersburg. "It's our view, by looking at the map, that we will win ...those precincts."
Republicans captured control of the U.S. Senate for the first time in eight years and also won Maryland's gubernatorial election. But most GOP challengers in the state struggled to make headway in districts that were designed by Democrats to be safe bets for the incumbents.
Republican control of the Senate will have a powerful influence on President Barack Obama's final two years in office as his administration prepares to negotiate with Congress over a rewrite of the nation's tax code, confirmation of a nominee for attorney general and a possible overhaul of immigration laws.
In Maryland, the high proportions of Democratic voters in most congressional districts acted as a buffer against the forces that were expected to deliver strong results for Republicans nationwide. Democrats were dealing with Obama's sagging approval ratings and challenges to Senate incumbents in seven states won by Mitt Romney in 2012.
Eight House incumbents — seven Democrats and one Republican — were up for re-election in Maryland. In the Baltimore region, Democratic Reps. Elijah E. Cummings, John Sarbanes and C.A. Dutch Ruppersberger, and Republican Andy Harris were all running in races that were not considered competitive.
Early results showed all incumbents, except for Delaney, with sizable leads.
Neither of the state's senators, Democrats Barbara A. Mikulski and Ben Cardin, was up for re-election.
Independent analysts predicted Delaney would win re-election.
But there were signs of life late in the race. Delaney, a former banker from Potomac, wrote himself an $800,000 check in the final days of campaigning and was airing a negative television ad that portrayed Bongino as too conservative for the district.
Bongino, of Severna Park, developed a national following with appearances on conservative media — including on Sean Hannity's radio program Tuesday afternoon — raised $1.2 million in campaign cash and aired his own television ads criticizing his Democrat opponent as unfriendly to business.
Delaney unseated 20-year incumbent Republican Rep. Roscoe G. Bartlett in 2012. The 20-point victory came after Democrats in Annapolis redrew the district to favor their party.
The 6th District includes Western Maryland and portions of Frederick and Montgomery counties.
A state Democratic official said there were about 8,000 absentee ballots in the district.
A spokeswoman for Bongino's campaign did not return a call seeking comment.
Sophia Ewing, a 46-year-old attorney who lives in Urbana, said she voted for Delaney partly because any Republican candidate would be intent on making "Obama's job just that much more difficult."
Ewing's neighbor, Kristen Keefer, wouldn't have a problem with that outcome. The 36-year-old mother of three said she voted for Bongino precisely because she isn't happy with the direction Democrats have taken the state and the country.
"I do not like the way things have been done for several years," she said.
Harris, the state's only Republican in Congress, was challenged by Democrat Bill Tilghman, a retired corporate lawyer from Centreville who put more than $220,000 of his own money into his campaign and raised another $300,000 from donors.
The 1st District, which includes the Eastern Shore and portions of Baltimore's northern suburbs, was once competitive. Harris rode the GOP wave of 2010 to unseat Democratic Rep. Frank Kratovil in one of the nation's most closely watched contests.
When Democratic lawmakers redrew the state's congressional map in 2011, they took Republican-leaning communities out of the 6th District and added them to the 1st. Harris, of Cockeysville, won re-election in 2012 with 63 percent of the vote.
"I look forward to continuing to work to promote and protect industries important to the First District," Harris said in a statement. "I'm humbled by the overwhelming support."
Reporter Charlie Hansler contributed to this article.