German Chancellor Angela Merkel's party CDU and its alliance FDP on Sunday lost control of her country's most populous state, North Rhine-Westphalia (NRW).

NRW, with 13.5 million voters, held its legislative election on Sunday from 8:00 a.m. (0600 GMT) to 6:00 p.m. (1600 GMT), just after the parliament approved the Greek bailout plan on Friday.

Latest exit polls from local television ZDF showed the Christian Democrats (CDU) only got 34.3 percent of votes, 10 points lower than the election five years ago, while its alliance the Free Democrats (FDP) got 6.6 percent.

Their major rivals the Social Democrats (SPD) got 34.7 percent, the Greens 12.4 percent and the Left Party 5.7 percent, which means the current CDU-FDP local government failed in the election.

As the supporting rates of CDU an SPD are very close, the make- up of NRW's next government was still unclear. The biggest possibility are big coalition government formed by CDU and SPD, or SPD plus the Greens.

"The SPD is back!" the party's leader in NRW, Hannelore Kraft, told jubilant supporters after the first exit poll results, adding that she wanted to rule with the Greens.

The failure of the current local government was widely expected by local media beforehand as polls have shown the local CDU-FDP coalition lack enough supports to win the election.

The approval of the unpopular Greek rescue package, pushed by Merkel, further worsen the attitude of the voters toward the states government.

A YouGov poll on Saturday showed that 21 percent of state voters would change their vote due to the Greek bailout.

"This is rare and will play a determining role," said by Klaus- Peter Schoeppner, head of the polling institute Emnid.

The election of NRW is traditionally taken as a weathervane for the national election. This defeat really challenged the Merkel's government, which operated from last October and added more uncertainties in the future.

In 2005, the CDU defeated SPD, which had ruled the state since 1966, before Merkel won the national election later that year.

In 1995, Johannes Rau from SPD formed a state administration with the Greens, while in the federal level, Gerhard Schroeder ( SPD) and Joschka Fischer (Green) beat Helmut Kohl's CDU in election to form a coalition government in 1998.

"This is a warning shot for the (federal) government parties," Vice Chancellor, FDP leader Guido Westerwelle said.

"This is a bitter defeat for the CDU in the state and federally, " said Gerd Langguth, political scientist at Bonn University and biographer of Merkel.

This failure would cause Merkel to compromise more with the opposition in future cases as her government lost a majority in Bundesrat, the upper house of the parliament, which represents 16 states.

At present, Merkel's coalition government owns 37 out of the total 69 Bundesrat votes, in which NRW has 6 votes. After Merkel lost control of these 6 votes, the opposition party will have more power to counter the government's future decisions, like tax cuts and health reforms. "The loss of the Bundesrat majority is not an insurmountable problem for the chancellor but it makes it more complicated for her coalition to get through some important policies," said Langguth.