BERLIN -- Chancellor Angela Merkel's party suffered a stinging defeat in Germany's most populous state, one likely to embolden her opposition both at home and abroad as the European debt crisis enters a critical new phase.
One week after Socialists seized the French presidency, the Social Democrats won the parliamentary election in North Rhine-Westphalia, early results and exit polls released Sunday showed. Norbert Rottgen, the lead candidate for Ms. Merkel's Christian Democrats in the state, conceded defeat and said he would be stepping down as the head of the party there.
Exit polls for German public television showed the Social Democrats winning 38.9 percent of the vote, an increase of 4.4 percentage points from two years earlier. While the results were not official, the party was likely to achieve a double-digit margin of victory. The Christian Democrats won just 26.3 percent of the vote, 8.3 percentage points less than in the previous election.
"This is a bitter day for us," Mr. Rottgen told supporters. "We have suffered a clear and decisive defeat."
He attempted in his concession speech to shoulder the blame, calling it "my loss" as a result of "my campaign, my themes," but the ramifications went far beyond the borders of the state.
With the Green Party's 11.8 percent of the vote, analysts say Hannelore Kraft, the Social Democratic state premier, will be able to form a left-wing coalition to govern the state with ease.
Mr. Rottgen ran against the debt-financed spending supported by Ms. Kraft, and even described the vote as a referendum on Ms. Merkel's Europe policies. Ms. Merkel has pressed debt-ridden European partners to pursue the path of harsh austerity policies even in the midst of recession.
The voters instead handed his opponent a significant victory.
The strong showing for Ms. Kraft and the Social Democrats as well as what the German news media described as a "debacle" and a "disaster" for the conservatives, sends a clear signal that Ms. Merkel could face a difficult road to re-election.
With nearly 18 million inhabitants, the state is home to more than one of every five Germans. A major defeat here for the Social Democrats in 2005 helped pave the way for the defeat of Ms. Merkel's predecessor, Gerhard Schroder, and her own rise to chancellor of Germany.
The result vaults Ms. Kraft, 50, a plain-spoken politician from the industrial Ruhr Valley, into the top rank of German politicians, prompting speculation that she might be the strongest candidate to lead the party against Ms. Merkel and potentially succeed her as chancellor.
Ms. Kraft is known as being down-to-earth and close to the people, still living in her hometown, Muelheim. Her party hopes she can help repeat the success on the national level, to Ms. Merkel's detriment.
Ms. Merkel's party has performed poorly in numerous recent state elections. Just one week ago the Christian Democrats were ousted from power in Germany's northernmost state, Schleswig-Holstein. The next federal election is scheduled for September 2013, but the recent defeats have led commentators to ask whether Ms. Merkel could be forced into an early election.
Voters across Europe have expressed their displeasure with Ms. Merkel's path, punishing the mainstream parties in Greece that signed the country's loan agreement with foreign creditors, which required deep spending cuts. In France's presidential election, Francois Hollande defeated President Nicolas Sarkozy, Ms. Merkel's close ally, in part by rejecting the German focus on austerity and promising more pro-growth policies.
The success of the Social Democrats in Germany could well give Mr. Hollande confidence in the difficult fiscal negotiations with Ms. Merkel.