After two years of investigations and scandal, David Rivera may owe his collapse at the polls on Tuesday as much to the changing politics of his newly created congressional district as to the crippling weight of humiliating headlines.

Rivera, a Republican, lost his congressional seat in an 11-point loss to Democrat Joe Garcia, whom Rivera had beaten to win the seat in 2010. Rivera has been hounded by criminal investigations since before he took office, hobbling his once-formidable fundraising and leaving him adrift in his own party.

Rivera says he lost the race not because of the press reports of the criminal investigations — probes whose very existence he once denied — but because of an unexpected wave of support for President Barack Obama, and weaker turnout for Republican presidential candidate Mitt Romney.

“I think an analysis of the results demonstrates that the presidential election had a significant impact on several congressional races, including my own,” Rivera said Wednesday. “It makes it tough for Republicans down ballot to be successful.”

Rivera also may have been undone in part by a changing climate in his own congressional district, which was redrawn by the Legislature earlier this year.

The new district, which stretches from Sweetwater through the southwestern suburbs of Miami-Dade to the Keys, is not as heavily Republican as the district that Rivera won in 2010. And a late Democratic voter registration push by the Obama campaign made the district even more difficult to hold.

Between June 1 and Nov. 1, more than 8,600 new Democratic voters in Miami-Dade were added to the district, outpacing new GOP voters, records show. Democrats now have a slight registration advantage in the district.

“This is becoming a Democratic district. This is a district that’s trending away from them,” said Jeffrey Garcia, a campaign consultant for Joe Garcia. (The two are not related.)

Citing an internal exit poll, Jeffrey Garcia said Joe Garcia soundly defeated Rivera among independent voters, and Garcia performed better than expected among Cuban American voters — Rivera’s longtime political base.

Rivera carried most of the precincts in the Sweetwater area, while Garcia won in much of Kendall and the Homestead area. In one Richmond Heights precinct, Garcia received 938 votes, compared to just 32 for Rivera. Garcia also carried Monroe County.

With the victory, Garcia becomes the first Cuban-American Democrat from Florida in Congress. Unlike Rivera and the other two Miami Republicans in Congress, Reps. Mario Diaz-Balart and Ileana Ros-Lehtinen, Garcia favors family travel and remittances to Cuba.

In his remarks to supporters Wednesday, Garcia said he hopes to work with Ros-Lehtinen and Diaz-Balart.

“We may be from different parties, but I respect them,” he said.

Speaking on Spanish language-radio Wednesday morning, Ros-Lehtinen said “things are going to work out fine” with Garcia in Congress, despite their differences over Cuba policy. The GOP maintained control of the U.S. House of Representatives.

Tuesday’s loss was the first election defeat for Rivera, the one-time leader of Miami-Dade’s Republican Party and a former state lawmaker whose influence and popularity withered under a series of criminal investigations and a scathing ethics probe.