Liberal Democrats in the Senate are warning President Barack Obama not to cave on taxes and entitlements in deficit talks set to begin this week, a move that could complicate efforts by the White House to win the backing of GOP leaders.

West Virginia’s Jay Rockefeller and Tom Harkin of Iowa are circulating a letter among their Democratic colleagues that calls on the president to stand firm on revenue, entitlement programs and spending cuts. They’re hoping to get as many as 30 Senate Democrats to sign on, Rockefeller said.

The letter, which was obtained by POLITICO, is dramatic in its policy prescriptions to avert the fiscal cliff.

For one, it says the president should insist on $1 in revenue for each $1 in spending cuts. It also says that the $917 billion in spending cuts enacted under last year’s agreement to increase the debt ceiling should be counted toward the next round of deficit reduction

Read more: Politico