Chancellor Angela Merkel on Monday downplayed her party's whipping in a weekend regional vote, and also offered strong backing to her embattled defense minister as Germany looks ahead to more state elections.

Merkel said 80 percent of the factors that influenced voters in Hamburg, Germany's second-largest city, in Sunday's election were local. She argued that allegations the defense minister plagiarized parts of his doctoral thesis played little or no part in the result.

Merkel's conservative Christian Democrats had been expected to lose power in Hamburg after a welter of local woes. Still, their thrashing was heavier than expected: they lost half their support and the opposition Social Democrats won a rare absolute majority in the state legislature.

Merkel conceded a "bitter defeat," but highlighted local sources — a popular mayor's resignation; botched education reform, that angered her party's voters; and the collapse of an experimental local coalition with the Greens, who are in opposition nationally.

Those "led to a loss of trust among voters," Merkel said. But she made clear that she sees no need to change policy ahead of six more regional votes this year — three of them late next month.

Merkel's defense minister, Karl-Theodor zu Guttenberg, has admitted "mistakes" but strongly denied the allegations of plagiarism. Still, they pose a risk to the credibility of a man regularly rated Germany's most popular politician and some opposition politicians have called for his resignation.

Late Monday, Guttenberg said he made "grave mistakes" and said he would give up his academic title.

Bayreuth University, which accepted the thesis, is looking into the matter. Merkel made clear that she stands by Guttenberg when asked if he would have to go if he loses his doctoral title.

"The defense minister has my full confidence," she told reporters. "Speculative questions are always difficult, but... I appointed Karl-Theodor zu Guttenberg as defense minister, I wasn't appointing a scholarly assistant."

Guttenberg will campaign for the upcoming state elections, "and as I see things he will get a lot of support from his audience," Merkel added.

Guttenberg still appears to have ordinary Germans' support. A weekend poll for ARD television found that 74 percent of respondents thought he shouldn't quit and only 22 percent said he should go. A Facebook fan page set up in Guttenberg's defense also had nearly 130,000 "likes" by Monday afternoon.

The Hamburg election offered unexpected comfort to Merkel's junior coalition partner in the national government, the pro-business Free Democrats, who saw their support increase despite dismal recent showings in national polls.

Their leader, Foreign Minister Guido Westerwelle, celebrated a "tailor-made start" to the election year and said it showed his party can win when it "fights and is united."