Sen. Bob Menendez’s (D-N.J.) opposition to a $410 billion omnibus spending bill has riled Democrats on Capitol Hill and in the White House, with some questioning whether members of the Senate Democratic leadership should take positions that endanger the passage of crucial legislation.

The newest addition to the Senate Democratic leadership team as chairman of the Democratic Senatorial Campaign Committee, Menendez had threatened for more than a week to oppose the omnibus because he disagreed with provisions relaxing travel restrictions to Cuba. Menendez, a Cuban American, reversed himself Tuesday afternoon after receiving assurances from Treasury Department officials that they would narrowly interpret the bill’s language.

Even though Menendez eventually came around to the Democratic leadership position that the bill must pass unchanged, senior White House officials, including Chief of Staff Rahm Emanuel, and rank-and-file Senators were steaming at Menendez’s intransigence. Those Democrats felt Menendez’s fight over the Cuba provision was a key reason for the Senate’s delay in passing the omnibus last week, several Democrats said.

Some Democratic sources said Emanuel and others raised the issue of whether Menendez should get to stay in the Democratic leadership lineup, particularly because before Menendez took the DSCC post, he lobbied hard for assurances that he would have a significant voice in larger leadership decisions.

Menendez said Tuesday that no one at the White House or in Senate Democratic leadership circles had expressed their irritation to him.

“I haven’t heard that at all,— he said. “I was over at the White House speaking to Rahm Emanuel about DSCC stuff, and he didn’t mention it at all, so they’ve had plenty of opportunities to say that.—

Still, Menendez’s Democratic critics said the delay on the omnibus opened their vulnerable Members up to more politically problematic GOP-sponsored amendments — including one on Congressional pay raises and another intended to strip earmarks out of the package. During amendment votes last week, the Senate took tough votes on earmarks linked to the lobbying under federal investigation and on abortion.

“There are people who did not want to take these votes, and they feel that if Menendez had come around sooner they wouldn’t be in this position,— said one senior Senate Democratic aide.

Another Senate Democratic source said, “Tempers flared last week, but I think it’s simmered down a bit— after Menendez confirmed he will help Democratic leaders overcome GOP procedural objections and clear the bill.

Senate Majority Leader Harry Reid (D-Nev.) had to extend debate on the bill Thursday because he could not get the 60 votes he needed to overcome a GOP-led filibuster. As many as four Democratic votes —including Menendez’s — were in question, and GOP supporters of the omnibus demanded more amendment votes for their Republican colleagues. But at press time, the Senate was slogging through the additional GOP amendments and was expected to pass the bill.

Menendez is hardly the only Democrat to express opposition to parts of the omnibus, but some Democratic sources said he should be held to a higher standard because he holds such a prominent leadership role. Plus, they said DSCC chairmen in particular should consider whether their actions might force vulnerable Members to take politically dicey votes.

Menendez said he has swallowed plenty of beefs with Senate legislation this year and last year to help Reid and the party, noting he voted for the Troubled Asset Relief Program and other measures despite reservations.

“I think I’ve been a great party player,— Menendez said. “When seven Democrats didn’t vote for the TARP funding, I did even though I had real reservations about it. When a whole host of Democrats including many in leadership questioned the president’s stimulus package when it first came out and said they needed to rework it, I wasn’t part of that. So it seems to me that there are double standards here.—

Sens. Russ Feingold (D-Wis.) and Evan Bayh (D-Ind.) have maintained that they will oppose the measure, while Sen. Bill Nelson’s (D-Fla.) concerns about the Cuba provisions — like Menendez’s — were assuaged by a letter from Treasury Secretary Timothy Geithner.

Though Democratic sources said Reid and other leaders were “annoyed— by Menendez’s stance, they said leaders felt confident that, had Reid pressed the issue to a vote last Thursday night, Menendez would have at least voted in favor of a procedural motion to end debate on the measure.

Even if Menendez had voted to cut off debate, Reid would likely have fallen one vote short because Republican supporters withheld their votes. But critics said Democratic infighting — especially in the leadership ranks — gave Republicans the opening they needed to force more amendment votes. Republicans have said they helped convince their centrists to hold out for more amendments by pointing out that even Democrats weren’t happy with the bill.

Still, the senior Senate Democratic aide said, “I honestly believe that Members of our caucus are willing to forgive him because he was doing this out of principle. … Ninety-nine times out of 100 Bob Menendez is going to be with you.—

The aide said Menendez received a round of applause in Tuesday’s weekly caucus lunch, when he announced he would be supporting the legislation.

Another Senate Democratic aide conceded that Senators were frustrated by the delay in passing the omnibus, but said it wasn’t all Menendez’s fault.

“Menendez got caught in the blame game,— the aide said.

Regardless, Menendez stood by his decision to call the Cuba language into question, saying he could not stand by and allow major changes to U.S. foreign policy pass without debate.

“Is it now acceptable to have a handful … of Members to determine foreign policy of the United States by sticking it in a must-pass bill and hoping everyone will just succumb because it must pass?— Menendez said. “That’s a dangerous precedent. It goes beyond Cuba.—

John Stanton contributed to this report.