Republicans force the removal of a measure that would cap insulin prices at $35 for private insurers.

Senate Republicans on Sunday forced the removal of a Democratic proposal that would have capped insulin prices at $35 for private insurers, even as seven Republicans joined all 50 members of the Democratic caucus in an effort to preserve the provision in the climate, tax and health care spending bill.

Left untouched as of Sunday morning, however, was a separate proposal that caps insulin at $35 per month for Medicare patients. More than 3.3 million people on Medicare receive some common form of insulin, according to the Centers for Medicare & Medicaid Services.

The cap for private insurers was widely viewed as a violation of the strict budgetary rules that govern the reconciliation process Democrats are using to fast-track the package and shield it from a Republican filibuster. But Democrats intentionally did not drop the provision, daring Republicans to vote on the Senate floor to strip it out.

“We have an opportunity to make a difference and permanently cap insulin,” said Senator Patty Murray of Washington, the chairwoman of the Senate health committee. She added, “This should not be a hard vote to cast.”

Republicans instead offered a separate amendment, which Democrats dismissed as too weak and opposed, before Senator Lindsey Graham, Republican of South Carolina, challenged the inclusion of the original private market proposal.

Seven Republicans joined the entire Democratic caucus in voting to preserve the insulin cap, but the 57-to-43 margin was not enough to meet the 60-vote threshold needed to overrule the challenge. The Republicans were Senators Susan Collins of Maine, Josh Hawley of Missouri, Cindy Hyde-Smith of Mississippi, Lisa Murkowski and Dan Sullivan of Alaska, and John Kennedy and Bill Cassidy of Louisiana.

Some lawmakers, led by Ms. Collins and Senator Jeanne Shaheen, Democrat of New Hampshire, had sought to pass a separate insulin pricing bill outside the budget process. But that required 60 votes to advance on the Senate floor, and the vote on Sunday showed that there was most likely not enough Republican support for that measure.