WASHINGTON (AP) — The White House threatened Wednesday to veto House Speaker John Boehner's backup plan for averting the "fiscal cliff," saying it was time for Republicans to stop political posturing and continue trying to reach a compromise deficit-cutting package.

Boehner, R-Ohio, proposed his so-called Plan B on Tuesday, a measure that would block tax cuts from being triggered Jan. 1 on everyone but those whose incomes exceed $1 million. The White House said Boehner's package did not raise enough revenue from the country's top earners, would leave too big a deficit-reduction burden on the middle class and omitted tax breaks used by families and businesses.

"The president urges the Republican leadership to work with us to resolve remaining differences and find a reasonable solution to this situation today instead of engaging in political exercises that increase the possibility that taxes go up on every American," White House Communications Director Dan Pfeiffer said in a written statement.