WASHINGTON — Congress is on the verge of adopting a federal budget this week without the threat of a government shutdown or any other form of economic or political crisis, a development so unusual that the institution suddenly does not resemble its most recent partisan self.

“Look at how we’re coming out of this bill – without rancor, without finger-pointing,” Senate Appropriations Committee Chairman Barbara Mikulski, D-Md., said Tuesday. “The tone has been one of courtesy and focusing on the compelling needs of the United States of America, which is to promote growth and reduce the debt. We have met that test.”

The first votes are expected Wednesday on the $1.1 trillion spending plan, less than 48 hours after negotiators introduced the 1,582-page spending agreement to fund government operations for the rest of the fiscal year.

The House is scheduled to vote on the measure Wednesday and the Senate could begin debating it Wednesday evening.

After months of negotiations, Democrats and Republicans seemed eager Tuesday to quickly approve the plan – even if they don’t have enough time to read it.

House Speaker John Boehner, R-Ohio, acknowledged to reporters that “I would like to have more time” to debate and pass the measure. But he added, “I think, under the circumstances, what we’re doing is appropriate.”

Government funding was set to expire Wednesday, but the House took steps Tuesday to approve a three-day extension of spending levels, giving Congress until Saturday to approve a final deal. The Senate was expected to approve the extension late Tuesday or early Wednesday.

Congressional Republicans cheered that the Pentagon will have about $20 billion in funding restored, even as domestic agencies endure further cuts, robbing President Obama of many of his spending requests.

But Democrats celebrated significant increases in funding for early-childhood education and their successful efforts to block Republicans from using the legislation to roll back Obama administration policies on the environment, immigration, infrastructure spending and foreign aid.

Eager to avoid another deadline-driven spending disagreement, Mikulski and House Appropriations Committee Chairman Harold Rogers, R-Ky., quietly began sketching out an agreement in the fall, even before a separate negotiating team finished the budget Congress approved last month.

During their talks, Mikulski, Rogers and their lieutenants agreed to avoid leaks. Their meetings alternated between House and Senate offices and concluded in the ornate Senate Appropriations Committee room on the first floor of the Capitol. Details of their agreement were provided late Monday.

On Tuesday morning, Washington awoke and began digging for potential deal-breakers. Few emerged.

“Nothing to rave about, controls the damage,” said a Democratic aide, who added that the weekly closed-door meeting of House Democrats produced few serious concerns from members.

Among Republicans, opposition came from familiar corners.

Rep. Thomas Massie of Kentucky, one of dozens of fiscal conservatives who often break with the GOP leadership on spending bills, said he doesn’t like the agreement but predicted it will pass. Massie was backed by outside conservative groups that hold sway over dozens of GOP lawmakers.

Heritage Action said the measure “takes the country in the wrong direction” while the Club for Growth announced opposition to the deal. The conservative Taxpayers for Common Sense was running a blog to document its concerns.