A $1 trillion spending bill unveiled Tuesday keeps most of the federal government funded through September. Here, The Post's Ed O'Keefe points out a few of the most notable components of the legislation. (Davin Coburn/The Washington Post)

The Senate will convene a rare Saturday session after it moved toward passing a $1.1 trillion bill to fund almost all of the government through most of 2015, after detractors on the right delayed final approval of the sweeping measure.

The opponents, who have been holding out for a chance to amend the legislation, were shut out by Senate Majority Leader Harry M. Reid (D-Nev.) and hold little chance of scuttling the omnibus spending bill, which must pass quickly to avoid a government shutdown. But they prompted the House to pass another funding extension as a backstop, giving senators more time to work through the political debate and procedural hurdles.

Late Friday, however, talks broke down on a plan to sign off on that extension in the Senate, setting up a series of procedural votes Saturday and dashing Reid’s hopes of a speedier process. “I would hope cooler heads prevail and we can move forward and get this done,” he said on the Senate floor earlier Friday.

If partisan acrimony does not subside, the government could face a shutdown Sunday morning.

While mostly liberal resistance had kept the bill’s fate in doubt in the House, conservative opposition in the Senate is now the focal point. On the right, the resistance was led by those who wanted to use the bill to confront President Obama on his executive actions on immigration.

“I think it is critical for the Senate to have an opportunity to have a clear up or down vote on funding President Obama’s illegal executive amnesty. I am using every tool available to help bring about that vote,” said Sen. Ted Cruz (R-Tex.).

After a speech to a near empty chamber, Cruz and several conservative allies blocked Reid’s effort to give the Senate the weekend off and return Monday, producing an angry exchange with the majority leader and setting up what could be a few dozen procedural votes on unrelated matters involving Obama’s executive and judicial branch nominations.

Sen. Mike Lee (R-Utah), a Cruz confidant, took to the Senate floor to slow Reid’s plans and try to force a vote on an immigration amendment that he, Cruz and others are pushing. The unexpected move will bring the chamber back into session after it appeared all but set to adjourn for the weekend.

The near-defeat of the spending measure in the House sharpened focus in the Senate on the odd-bedfellows political coalition that almost torpedoed the bill.

Liberals anger has centered on a provision that would loosen a key regulation on big banks. The populist anti-Wall Street faction was led by freshman Sen. Elizabeth Warren (D-Mass.).

Enough is enough,” she said on the Senate floor Friday. “Washington already works really well for the billionaires and big corporations.”

In a random twist, the measure’s two most outspoken opponents met on the Senate floor late Friday. Cruz blasted the bill in a speech as Warren presided over the chamber in her role as the designated Senate president, a duty reserved for the most junior senators.

But it was Cruz and Lee’s fight that seized the attention Friday, overshadowing Warren’s protests.

While opponents of the bill were clinging to slim hopes that they could derail the legislation, they stopped short of pledging to block it altogether.

On Saturday, Senate Democrats still hope to pass the second stopgap funding extension already approved by the House. It would clear the way for Congress to work until Wednesday night, if needed, to complete its consideration of the measure, which would fund the government through the end of next summer. Current spending expires at the end of the day.

The one exception is the Department of Homeland Security, which would be funded by the spending bill only through late winter amid the fight over Obama’s decision to halt the deportations of millions of undocumented immigrants. The department oversees government operations involving immigration, including the U.S. Customs and Border Protection Service.

Sen. Jeff Sessions (R-Ala.), another critic of the immigration action, conceded Friday that strong GOP support for the spending bill in the House on Thursday night makes it less likely for his perspective to prevail. “I adhere to the view that Congress should not fund a program that we think is unworthy and unlawful, but that’s been decided by the House,” he said.

Warren sparked a Democratic revolt in the House this week by speaking out against the legislation. But she hadn’t indicated she was ready to block the bill. Neither had Sen. Bernard Sanders (I-Vt.), another liberal stalwart.

Warren teamed up with Sen. David Vitter (R-La.) to try to fight the banking provision. The two introduced an amendment to remove the language from the bill that loosens the restrictions on banks when it comes to risky derivative transactions.

Meanwhile, Sessions, Cruz, Vitter and Lee were hoping to force a vote on their proposal to defund parts of the federal government tied to Obama’s immigration actions.

But Reid used parliamentary tactics to block both amendments.

Even as the Senate focused in on a spending bill vote, it still had other business to complete, including votes on judicial nominations, a terrorism insurance bill and extending a collection of tax breaks.

The funding legislation became ensnared in a fight over Obama’s judicial nominees, whose chances at confirmation decrease dramatically next month when Republicans take control of the Senate. Minority Leader Mitch McConnell (R-Ky.), who is set to succeed Reid as the majority leader, suggested his side was willing to speed the entire process along, including passage of a terrorism insurance bill and extending a collection of expired tax breaks.

“I want everybody to understand that it’s possible to finish tonight,” McConnell said.

But Republicans were not willing to let the nominees easily pass and instead Democrats need more time next week to clear procedural hurdles for confirmation votes. “We’re not going to finish tonight,” Reid said on the Senate floor.

In other business, legislation setting Pentagon policy for the next year passed the Senate on Friday. Senators also confirmed two members of a federal broadcasting board and five ambassadors to Cape Verde, Iceland, Palau and other places.

In an effort to try to ensure passage of the spending bill, Obama reiterated his support, saying, “This, by definition, was a compromise bill.”

“Had I been able to draft my own legislation, get it passed without any Republican votes, I suspect it would be slightly different,” the president said later. “That is not the circumstance we find ourselves in, and I think what the American people very much are looking for is responsible governance and the willingness to compromise.”

Speaking on the Senate floor after Warren on Friday evening, Sen. Lindsey O. Graham (R-S.C.) warned opponents of the bill against blowing it up.

Graham pledged to vote for the bill, even as he acknowledged “knowing it’s not perfect.”

One lawmaker who appeared to be tiring of all the extended talks was Sen. John McCain (R-Ariz.).

“It’s ridiculous,” he told reporters outside the Senate chamber. “A lame-duck session after the American people have spoken.”