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 A. Mikulski (D-Md.) said in an interview 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 on the $1.1 trillion spending plan, are expected Wednesday, 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 plans to vote on it at noon Wednesday.

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 A. 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.”

“Look at how we’re coming out of this bill — without rancor, without finger-pointing,” Senate Appropriations Committee Chairman Barbara A. Mikulski (D-Md.) said Tuesday. (JONATHAN ERNST/REUTERS)

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 that 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 (Ky.), 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.

But GOP aides said that only few specific objections were raised Tuesday during their weekly meeting: Among those were complaints by lawmakers from Utah and Wyoming that the spending agreement did not pay for an Interior Department program that compensates local governments for land the federal government owns. Aides in both parties said the matter is likely to be sorted out in the forthcoming Farm Bill.

Beyond that issue, Republicans were especially pleased that the spending deal would redistribute money from a public health fund established by the Affordable Care Act and bar the administration from using the money to pay to implement the new law. The bill also would cut $10 million for the Independent Payment Advisory Board, an entity that Republicans refer to as the “death panel” established to advise government officials on health-care issues.

Republicans scored victories on several issues of concern to GOP base voters, including energy policy, gun control and the attack on Sept. 11, 2012, at a U.S. diplomatic outpost in Benghazi, Libya.

The measure essentially would stop the enforcement of new standards that would ban the use of incandescent light bulbs. The change was proposed by the George W. Bush administration and implemented by the Obama White House despite sustained consumer demand for the bulbs.

The agreement also would restrict the Justice and Homeland Security departments from establishing programs similar to the controversial Operation Fast and Furious gun-running program. It would require DHS to provide detailed reports on its purchase and use of ammunition. And the Libyan government would not receive any foreign aid until the State Department “confirms Libyan cooperation” with ongoing investigations of the Benghazi attack.

Democrats praised big spending increases for Head Start, including new money for Early Head Start and grants that would expand preschool programs. Aides also noted that Democrats blocked GOP attempts to prevent the Environmental Protection Agency from regulating greenhouse gas emissions and to repeal new clean water regulations and that Democrats stopped efforts to prohibit the Justice Department from using federal money to challenge state immigration laws in court.

The omnibus measure includes several changes in response to reports of outlandish government spending. It would impose bans and limits on certain conferences, official travel and employee awards. After twin controversies, the Internal Revenue Service faced special scrutiny. The agency would be forbidden from using money to target certain political groups. And the IRS could not use authorized money to produce “inappropriate videos” after investigators discovered worker-training videos that spoofed “Star Trek” and “Gilligan’s Island.”

Fulfilling a request by Obama, the agreement would impose a pay freeze on Vice President Biden and senior political appointees. The legislation also would bar the use of federal money “for painting portraits” — a blow to members of Obama’s Cabinet.

But Congress would continue its long-standing tradition of compensating the family of a lawmaker who dies in office. Tucked inside the legislation is a standard $174,000 bereavement payment to Beverly A. Young, the widow of C.W. Bill Young (R-Fla.), a former chairman of the House Appropriations Committee.