* Euro crisis deal-broker has Merkel backing
* Rivals include Latvia's Dombrovskis, France's Barnier
* Centre-right group EPP to chose lead candidate in March
By John O'Donnell
BRUSSELS, Feb 27 (Reuters) - Veteran Luxembourg politician Jean-Claude Juncker has won the backing of Germany's major conservative party in the race to become European Commission president, as he officially submitted his bid to become the centre-right candidate.
The move, which had been expected, puts one of the European Union's most experienced deal brokers in contention for arguably its most influential job, although Juncker, who once told a conference he sometimes lied and favoured "secret, dark debates", has alienated some by his frankness.
The European People's Party (EPP) on Thursday announced the former Luxembourg prime minister's candidacy. He will compete with Valdis Dombrovskis, previously Latvia's prime minister, for a post with power over policy affecting 500 million Europeans.
Michel Barnier, the European commissioner who oversaw banking reform, is also expected to seek backing from the centre-right EPP, when members meet to chose their lead candidate ahead of the European Parliament elections in May.
But Juncker has the support of German chancellor Angela Merkel and her party of Christian Democrats, making him the likely favourite when the EPP, Europe's largest political grouping, gathers on March 6-7 in Dublin.
"Commission president is not a position for learning on the job," said Elmar Brok, an influential member of Germany's Christian Democrats in the European Parliament. "Juncker is someone with broad European experience."
Part of a generation of old-school politicians, Juncker played a significant role in handling Europe's debt crisis, leading the Eurogroup of euro zone finance ministers.
For decades, elections to the European Parliament have been a secondary affair, with a low turnout. That has changed since a new EU treaty in 2009 gave the parliament more say in policy and a role in determining who should become the Commission president.
And following the worst financial crisis in a generation, many observers expect radical nationalist parties to win unprecedented support when voters from across the 28-member European Union go to the polls.
Whichever political group emerges as the largest bloc in parliament following the May 22-25 elections is expected to have first claim on the presidency post, although the choice also has to be approved by EU leaders.
A new Commission president - replacing Jose Manuel Barroso, who has held the post since 2004 - will assume office for five years from November, taking charge of an institution responsible for proposing EU law and policing existing rules. The Commission also leads trade negotiations and coordinates foreign policy.
Juncker was caught up in a spying scandal in Luxembourg last year and his Eurogroup successor and Dutch finance minister, Jeroen Dijsselbloem, described him on Dutch television as a heavy drinker and smoker. Juncker has dismissed these suggestions.
He disarmed but often irritated ministers with his dry sense of humour, speaking openly of having to lie to the media and discussing his problems with kidney stones.
The Socialists and Democrats, the second-largest group in the European Parliament, have selected Germany's Martin Schulz, the president of the European Parliament, as their candidate.