WASHINGTON ― In the upcoming budget debate, a group of moderate Democrats are trying to set a floor for 2022 defense spending before progressive Democrats try to push it lower.

Leaders of the House’s Blue Dog Coalition say they oppose calls to fund any less than the requested $753 billion national defense budget for fiscal 2022 — which included $715 billion for the Pentagon. The stance adds fuel to an already complicated budget debate, where Democrats are split and key Republicans are pushing for a boost.

“We believe this is a strong and sensible funding request, and we oppose calls to authorize or appropriate funding below this level,” the six lawmakers said in a June 24 letter to leaders of the House Armed Services Committee and House Appropriations Committee.

The letter’s signatories are Reps. Mikie Sherrill of New Jersey; Tom O’Halleran of Arizona; Stephanie Murphy of Florida; Ed Case of Hawaii; Abigail Spanberger of Virginia; and Kurt Schrader of Oregon.

A group of six is significant in the House, where the 220-211 partisan split means Democrats can only lose four members on any party-line vote. The letter comes as some Democrats worry that appropriations bills will have difficulty garnering the necessary support to advance before the August recess.

“My understanding is that it isn’t just my bill that’s in trouble, just appropriations across the board,” Appropriations Subcommittee on Homeland Security Chairwoman Lucille Roybal-Allard told Congressional Quarterly on Wednesday. “A lot of the subcommittees are having problems for different reasons.”

The House Appropriations Committee’s Defense Subcommittee is set to release its proposed defense spending bill this week.

The letter from the Blue Dog bloc emphasizes President Joe Biden’s budget request, which sets its signatories at odds with a group of 50 House progressives who have called on Biden to “significantly” slash defense. However, it does not rule out an alliance with key Republicans, who have said defense must rise 3-5 percent above inflation to counter a rising China.

The group of six did not like everything about Biden’s budget. The lawmakers joined bipartisan pushback against the request’s formulation of the China-focused Pacific Deterrence Initiative, saying Congress should “provide no less than $4.68 billion” for FY22, as outlined by Indo-Pacific Command’s Section 1251 report. (Defense Secretary Lloyd Austin has acknowledged the criticism and said the Pentagon will work with Congress to resolve issues.)

Also on Thursday, several Senate Republicans held a news conference to say Biden’s defense spending proposal is too low, and they challenged moderate Democrats in the Senate to join them. Sen. Dan Sullivan, R-Alaska, said moderate Democrats and Pentagon leaders privately told him they are unhappy with the budget request.

“We think national defense should be the top priory of the Congress, not the last priority, and I think we have the American people behind us on this,” he said. “I think there’ll be tough votes for Democratic senators from states ― Virginia, Georgia, Arizona ― think about those states, very pro-military states.”