By Erik Kirschbaum

BERLIN, Dec 21 (Reuters) - The German government should push through a new economic stimulus package even if it has to ignore a veto threat by some conservatives demanding simultaneous tax cuts, Vice Chancellor Frank-Walter Steinmeier said on Sunday.

Steinmeier, whose Social Democrats (SPD) share power in an awkward grand coalition with Chancellor Angela Merkel's Christian Democrats and the CDU's Bavarian sister party, the Christian Social Union, said the stimulus was urgently needed.

Merkel said on Saturday her government would pass a second round of measures in January following a first step in December to help the economy fight recession.

But the conservative CSU has vowed to block that unless tax cuts to supplement the new spending are included.

"The coalition has enough votes to pass the measure even without the CSU," Steinmeier told Bild am Sonntag newspaper when asked if the CSU threat would thwart the deal. "No one can stand in the way of the investment programme that is urgently needed."

Yet it is unlikely the CDU would pass any measure without CSU backing even though Merkel ALSO opposes any tax relief before September's federal election. The CDU and CSU form a close joint parliamentary group.

Steinmeier, who will run against Merkel in September, said the tax cuts the CSU wants primarily benefit those with high incomes and they are likely to save rather than spend tax cuts.

"We don't want the money to end up in savings accounts but instead we want the money to be used to jump start consumption," said Steinmeier, who is also Germany's Foreign Minister. No income tax is paid by 22 million people with no or low wages.