A Swedish far-right party that made strong gains in the September election says it won't vote for the minority government's budget, likely forcing the collapse of Prime Minister Stefan Lofven's minority government.

Sweden Democrats spokesman Mattias Karlsson said Tuesday his group would attempt to force the government to resign by siding with the rest the center-right opposition in Wednesday's budget vote.

It was not immediately clear if Lofven, a Social Democrat, would resign. He has previously told the daily Dagens Nyheter he could not remain as head of the government if it could not gain a majority in the budget vote.

Lofven came to power after the Sept. 14 elections as the head of a coalition with the Greens, promising to reverse many reforms by the previous center-right government.