By Michael Teitelbaum, CQ Staff

The Democratic Party has officially gained another U.S. House seat, with the confirmed victory by county prosecutor Frank M. Kratovil Jr. in Maryland’s 1st Congressional District. State Sen. Andy Harris, the Republican nominee in the contest, conceded defeat Tuesday morning after nearly a week of absentee and provisional ballot counting left Kratovil with a firm lead of more than 2,000 votes.

The victory capped a remarkable rise for Kratovil, who entered the race as a distinct underdog in a conservative-leaning district — encompassing Maryland’s Eastern Shore region and pockets of suburban and exurban voters north and south of Baltimore across the Chesapeake Bay — that had been a stronghold for nine-term Republican Rep. Wayne T. Gilchrest . But Kratovil, who was aided by the national Democratic Party’s momentum throughout this election year, also benefitted enormously from a deep rift within Republican ranks resulting from the conservative Harris’ defeat of the more moderate Gilchrest in the district’s Feb. 12 primary.

Gilchrest and his loyalists were embittered by attacks from Harris and outside conservative groups, such as Club for Growth, that questioned his credentials as a Republican. And Kratovil soared into serious competition in early September when Gilchrest crossed party lines to endorse him to be his House successor.

Kratovil’s win — with 49 percent of the nearly complete vote count to 48.4 percent for Harris and 2.4 percent for Libertarian Party nominee Richard James Davis — guarantees that the Democrats will expand their House majority to at least 255 seats with a net gain of at least 20 seats that were held by the Republicans.

There still are five House contests that have not yet been decided. Three are close Nov. 4 general elections for Republican-held seats, in which votes still are being counted: one, in Virginia’s 5th District, in which the Democratic candidate currently leads, and two, in Ohio’s 15th District and California’s 4th District, in which the Republican candidates hold narrow leads.

There also are two general elections in Louisiana that are being held Dec. 6 because of delays resulting from an early September hurricane that forced a postponement of the state’s primary elections. The contest for a Republican seat in the 4th District is a highly competitive Democratic takeover bid; the other, in the overwhelmingly Democratic 2nd District, appears certain to stay in that party’s hands.

Barack Obama , the Democratic president-elect, also will be greeted at his Jan. 20 inaugural ceremonies by a greatly expanded Democratic caucus in the U.S. Senate. The Democrats already have secured a gain of six Republican-held seats, expanding their effective control from the current razor-thin majority of 51 seats to at least 57. Three races, all for Republican-held seats, remain undecided: in Alaska, where many ballots have yet to be counted; Minnesota, where the race is so close an automatic recount will be required; and Georgia, where it appears a Dec. 2 runoff election will be needed to decide the winner.

How Kratovil Won

Democratic Rep.-elect Kratovil had plenty of assistance — both intentional and unintentional — in the Maryland House race. Running in a district where President George W. Bush took 62 percent of the vote in 2004 and where Gilchrest was re-elected with 69 percent in 2006, Kratovil would have been a unlikely winner this year had the primary defeat of the incumbent not caused a rupture within the ranks of the local Republican Party. But he was lifted by significant aid provided by the national Democratic strategists and the state Democratic organization that dominates Maryland’s politics, which sensed opportunity in Maryland 1 and elevated the race there into one of their top-priority takeover bids.

Kratovil received strong backing from a party leadership that include Gov. Martin O’Malley; 5th District Rep. Steny H. Hoyer , the House majority leader; and 8th District Rep. Chris Van Hollen , who chairs the Democratic Congressional Campaign Committee (DCCC), the campaign arm of the House Democratic caucus.

The DCCC doubled down on the contest by pouring nearly $1.9 million into independent expenditures, mainly for media advertising, to try to influence the race in favor of Kratovil. That helped the Democratic nominee overcome the advantage that Harris held as Oct. 15 in direct campaign contributions to the candidates — $2.9 million to $1.8 million for Kratovil — although Harris had to spend much of that money very early this year in his primary campaign against Gilchrest.

Kratovil’s win gives Democrats seven of Maryland’s eight House seats to go with both Senate seats, the governor’s office and big majorities in the state legislature. Obama carried the state by a near-landslide margin, and while he trailed Republican John McCain in the 1st District, the margin was not nearly as wide as in the 2004 presidential races.