Potomac businessman John Delaney handily beat Republican U.S. Rep. Roscoe Bartlett on Tuesday, as Maryland Democrats realized their plan to take control of the state's 6th Congressional District, one of the state's last remaining Republican strongholds.

Delaney defeated the incumbent Bartlett, who represented the 6th District for 20 years but could not overcome a wealthy challenger in parts of Maryland that Bartlett never had to campaign in before.

"We have to put partisan bickering aside, and because of your work, because of your commitment, and because of your dedication, and because of your support, I have the opportunity now to play my part in making that happen," Delaney told supporters at his victory party in Potomac.

More rural, northern Maryland areas that the 86-year-old Bartlett had represented for the last decade were replaced this year by hundreds of thousands of voters in parts of liberal Montgomery County -- a move by Gov. Martin O'Malley to shift the once-Republican district into a majority Democratic region.

In 2010, 208,000 registered Republicans easily outnumbered the district's roughly 160,000 registered Democrats, according to the state Board of Elections.

Delaney will represent roughly 193,000 registered Democrats, compared with 146,000 registered Republicans.

"It's tough, it's tough," Bartlett said while campaigning in Ijamsville on Tuesday afternoon. "We had 357,000 people in Montgomery County that we had to get acquainted with."

An effort to overturn the gerrymandered redistricting map that made Bartlett vulnerable to a Democratic challenger fell short, as voters upheld what one study called some of the least-compact districts in the country.

Maryland voters overwhelmingly supported the new congressional map.

Delaney downplayed the redistricting process and pointed to shared concerns among residents of Western Maryland and Montgomery County -- jobs and education -- that he promised to tackle by getting the government and the private sector to work together.

While happy to see Bartlett unseated, Delaney wasn't Maryland's Democratic leaders' first choice as a candidate for congress -- O'Malley and others endorsed state Sen. Rob Garagiola, D-Montgomery, in the primary election.

But Delaney's fundraising edge and endorsements from the likes of former President Clinton helped the Potomac resident rout Garagiola in April, and Democrats were quick to rally around Delaney to add a seventh Maryland Democrat to the U.S. House.

Delaney's fundraising prowess carried over into the general election, as he outraised Bartlett by more than three to one during the 2012 election cycle.