STOCKHOLM (Reuters) - The anti-immigration Sweden Democrats are more popular than ever, winning over voters from the centre right and centre left before an early election in March they helped trigger by voting down the government's budget, a poll showed.
September's election returned a minority centre-left government and left the Sweden Democrats holding the balance of power as the country's third-largest party.
Showing their growing clout, the party this month blocked the budget by backing a rival finance bill put forward by the centre-right Alliance opposition, leading Social Democrat Prime Minister Stefan Lofven to call the new election just two months after taking power.
With the left and right roughly equal in size, the growing powerbase of the Sweden Democrats could leave them again as kingmakers in a fractured parliament as each side try to lash together a stable government.
The poll for broadcaster TV4 released on Tuesday showed the party with 16.0 percent of the vote, up 3.7 points from a month earlier and ahead of the 12.9 percent they got in September.
Pollsters Novus said that was the highest level of support seen in one of its surveys for the party, which wants to cut asylum seeker numbers by 90 percent.
Novus said the Sweden Democrats were picking up support mainly from the Moderates, the biggest centre-right party.
Supporters of the Social Democrats, which lead the minority coalition government, are also switching to the Sweden Democrats, Novus said, though in smaller numbers.
The Sweden Democrats moved from the far-right fringe to take their first seats in parliament in 2010.
They doubled their support in September's vote and have threatened to bring down any government that does not curb rising immigration.
The poll showed the four parties of the centre-right opposition Alliance backed by 38.5 percent of voters, down more than 3 points from November, before the budget crisis.
The coalition government - plus the Left Party - got 43.3 percent, slightly above the last poll.
The centre-left's improvement was down to increased support for the Social Democrats who saw their backing rise to 32.0 percent, up 3.4 points from November, Novus said.
Junior coalition partner the Green Party saw its support decline 1.9 points to 6.0 percent. Undecided voters totalled 8.5 percent.
The poll of 1,786 people was conducted between Dec. 3 to Dec. 14, after Lofven called the snap election.
(Reporting by Simon Johnson; Editing by Alison Williams)