WASHINGTON — The massive spending bill unveiled Tuesday evening by congressional leaders includes $554 billion for the Pentagon, including base-budget growth.

After a two-day delay, leadership and the heads of the Appropriations committees struck a deal on a "cromnibus" spending bill, which would fully fund 11 departments through the fiscal year and the Department of Homeland Security through February.

The term "cromnibus" refers to the measure's appearance as an omnibus appropriations bill because of its 11 full-year spending measures. The first two letters refer to a continuing resolution (CR) for Homeland Security, a Republican response to the president's action on immigration.

In what has become a holiday season tradition on Capitol Hill, the spending measure must pass by Thursday at 11:59 p.m. (EST) to avert a government shutdown that Republican leaders worked hard the last two weeks to head off. To that end, the chairs of the House and Senate Appropriations committees late Tuesday urged both chambers to pass the cromnibus "as soon as possible."

For the Defense Department, the legislation would provide $554.1 billion for fiscal 2015, just smaller than the $554.3 billion the Obama administration requested.

But the bill's $490.1 billion base 2015 Pentagon appropriations bill, if enacted this week, would be $3.3 billion larger than the amount allocated for fiscal 2014.

The measure would give the White House most of the funds it requested, including $3.4 billion of the $5.6 billion it recently asked for to fight the Islamic State in Iraq and Syria. It proposes $64 billion for the Pentagon's overseas contingency operations (OCO)account; with the war in Afghanistan winding down, that level would be about $21 billion less than the 2014 enacted level.

A summary of the cromnibus released by congressional leaders and top appropriators states it includes $93.8 billion for total Pentagon procurement, a $1 billion hike from the previous year. For R&D, DoD would get a total of $63.7 billion, up $700 million from 2014.

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Amid worries about the military's readiness, appropriators are proposing $161.7 billion — $1.8 billion more than last year — for operation and maintenance accounts.

The House and Senate appropriators merged the plans their respective committees had approved for blocking the Air Force's plans to retire its A-10 attack plane fleet. They adopted the House panel's language and the Senate committee's funding level.

Adopted as a floor amendment, the House language would prohibit the service from using any 2015 funds to retire its A-10s. The Senate Appropriations Committee passed a defense spending bill that proposed $338 million to keep the A-10s flying for one more year.

The bill would give DoD at least $240 million more than requested for the F-35 fighter program to buy four more jets than planned.

The measure also substantially ramps up funding for the Navy's E/A-18G electronic warfare jets to $1.4 billion, providing enough monies to buy 15 in fiscal 2015.

For the Navy, the legislation provides a $1 billion funding hike above the request for one San Antonio-class amphibious transport ship. It also would keep the American aircraft carrier fleet at 11, allocating $483.6 billion to refuel the USS George Washington.

The shutdown-skirting measure would increase funding for joint US-Israeli missile defense programs by $172 million. For the much-ballyhooed Iron Dome program, the appropriators doled out $175 million more than the $176 million the White House requested, for a program total of $351 million.

The National Guard and Reserve would get $1.2 billion more than requested to "enhance" their equipment, according to the summary.

As tensions in Eastern Europe continue to simmer, the appropriators propose $810 million for what's called the "European Reassurance Initiative," including $175 million for equipment and "associated support" for indigenous forces in Ukraine and the Baltics.

The bill appears headed next for the House Rules Committee, then to chamber floor. Senior lawmakers remained cautiously optimistic as of late Tuesday afternoon that both chambers could waive certain floor rules to pass the cromnibus before the Thursday evening deadline.

"Federal government's going to run out of money in two days," Senate Majority Leader Harry Reid, D-Nev., told reporters. "There's no reason the government should shut down. And we're ready to pass a yearlong spending bill to take care of this."

House Appropriations Committee Chairman Hal Rogers, R-Ky., and Senate Appropriations Chairwoman Barbara Mikulski, D-Md., are pushing their colleagues to adopt the cromnibus.

"More than two months into the fiscal year, it's time we end government on autopilot so we can turn our focus to meeting the day-to-day needs of Americans and long-range needs of the nation," the duo said Tuesday evening in a joint statement.

"This bill fulfills our constitutional duty to fund the government, preventing damage from shutdown politics," they said. "While not everyone got everything they wanted, such compromises must be made in a divided government. These are the tough choices that we must make to govern responsibly and do what the American people sent us here to do."