Republicans in Congress hardened their resistance to President Barack Obama’s proposed higher taxes for top earners and demanded a spending-cut plan, as lawmakers in both parties said it’s becoming less likely an agreement can be enacted before Christmas.

Obama’s budget plan is “mainly tax hikes,” House Speaker John Boehner told reporters Wednesday in Washington. “We’ve got some serious differences.” During a phone call Tuesday, Boehner said, he and the president were “frank” about “how far apart we are.”