Three Republican senators firmly opposed the latest plan to repeal the Affordable Care Act, leaving Senate leaders short of the votes needed for passage and causing the bill to collapse.

Republican leaders were trying to pass the bill in the Senate before the end of the month to protect it from a Democratic filibuster. They will now likely end the year without fulfilling their long-standing promise to repeal the health law.

In recent months, 13 Republican senators from 12 states have rejected at least one of the Senate’s five major repeal efforts. Opposition has come from the party’s moderates and hard-liners, but for different reasons.

Republican senators who publicly opposed a repeal bill, arranged by their ideology scores Number of bills opposed 1 2 3 4 5 ← Less conservative More conservative → ← Less conservative More conservative → Note: Ideology measurements are based on DW-NOMINATE scores, which are based on Congressional votes.

One of the proposals, an initial version of a repeal-and-replace bill, collapsed in mid-July before a vote could be held. Three others were voted down the next week. And a fifth, last-ditch effort was thwarted on Monday, when Senator Susan Collins of Maine announced her opposition, calling the plan “deeply flawed.”

nyt_name state_abbr Early BCRA Repeal and replace Partial repeal “Skinny” repeal Cassidy-Graham Susan Collins Me. No No No No No John McCain Ariz. No No No Rand Paul Ky. No No No Lisa Murkowski Alaska No No No Dean Heller Nev. No No Mike Lee Utah No No Jerry Moran Kan. No No Bob Corker Tenn. No Tom Cotton Ark. No Lindsey Graham S.C. No Lamar Alexander Tenn. No Shelley Moore Capito W.Va. No Rob Portman Ohio No

Several of the most moderate Republican senators have expressed concern that deep Medicaid cuts would hurt vulnerable populations.

Among them are Ms. Collins and Senator Lisa Murkowski of Alaska, who both voted against all three Senate bills in July. Both have expressed concerns about how the bills would impact people in their states. Ms. Murkowski remains undecided on the latest plan.

Senator John McCain of Arizona, who cast the decisive vote against one of the bills in July, has been critical of the Senate legislative process that avoided hearings or formal bill-drafting procedures. He also expressed concerns that the repeal bill would pass with no Democratic votes, and has urged his party to work toward a bipartisan plan.

Other senators opposed the bills for different reasons. Conservatives, like Senators Mike Lee of Utah and Rand Paul of Kentucky, would rather have a full repeal of the Affordable Care Act. Mr. Paul said last week that he would not vote for the new bill.