Key German state votes

State elections inviting over 13 million people to vote in North Rhine-Westphalia are seen as the biggest political barometer ahead of general elections in Germany next year.

The country's most populous state is not as wealthy as Bavaria, but is also traditionally a more hotly-contested state than the conservative-dominated south.

Opinion polls point towards success for the opposition Social Democrats (SPD) and Greens, who had ruled in a minority government for two years prior to the vote, but it's unclear whether the alliance can secure a majority.

A survey by state broadcaster ARD published on May 3 put the SPD in the outright lead with 38.5 percent of the vote, while predicting that the Greens might court a further 11 percent - putting the pair almost precisely on the 50 percent threshold.

Chancellor Merkel's Christian Democrats (CDU) polled at 30 percent in the same survey, with their current coalition allies in the federal government, the pro-business Free Democrats (FDP), at a meager 6 percent.

The Left party was polling at 4 percent, just below the 5 percent required to qualify for seats in parliament, while the relative newcomers from the Pirate party enjoyed an estimated 7.5 percent of the vote - representing a slight drop compared to the previous ARD-commissioned poll.

Kraft versus Röttgen

The leading personalities in the vote are the SPD candidate for state premier, Hannelore Kraft, and her CDU counterpart, Environment Minister Norbert Röttgen. Kraft polls markedly higher among voters than Röttgen.

Kraft was the state premier of the minority government in North Rhine-Westphalia and has said her target is to consolidate the existing SPD-Green alliance to hold a majority - something that appears possible but by no means guaranteed.

Röttgen, meanwhile, sought to make light of his deficit in the polls when speaking to the German dapd agency in Düsseldorf on Friday.

"In the surveys, 40 percent of those questioned say they don't yet know whether they will vote at all and for whom they would vote," Röttgen said, adding that this showed how open the race really was.

With the ruling coalition losing ground in a string of recent state votes, the ballot in North Rhine-Westphalia will have the undivided attention of federal leaders in Berlin, with general elections scheduled for 2013.

A national poll by the Emnid institute, to be published on Sunday in the mass-circulation Bild am Sonntag weekly, also suggested that the SPD and Greens combined were a slightly stronger force than the Christian Democrat alliance and the FDP combined - albeit with Merkel's conservatives still by far the strongest single party in Germany.

msh/tj (AFP, dpa, dapd)