Republicans are working on their bill as insurers around the country are announcing their intentions for 2018. On Monday, the last major insurer remaining in Iowa said it planned to stay in the Affordable Care Act’s marketplace next year. The insurer, Medica, said that it expected to offer plans statewide, even after two competitors said they would pull out, but that it was seeking rate increases averaging 43.5 percent.

“Iowa’s individual market remains unsustainable and needs a fix from Congress,” said the state’s insurance commissioner, Doug Ommen.

Republicans, who hold 52 seats in the Senate, are planning to pass their repeal bill using special budget rules that would bypass a Democratic filibuster. But they can afford to lose only two votes, with Vice President Mike Pence breaking a tie, and more than two Republican senators have expressed qualms, from moderates like Susan Collins of Maine and Lisa Murkowski of Alaska to conservatives like Rand Paul of Kentucky and Mike Lee of Utah.

So far, Republican senators have been unable to reach a consensus on a repeal bill, facing internal divisions over issues like the future of the expansion of Medicaid under the Affordable Care Act, the rate at which Medicaid payments to states would grow in future years and federal funding for Planned Parenthood.

In impassioned speeches on the Senate floor on Monday night, Democrats complained that the bill was being developed out of public view. Before Congress adopted the Affordable Care Act, Democrats held numerous public hearings, and the Senate debated the measure on the floor for 25 days.

Senate Republican leaders plan to push through their repeal bill under arcane budget rules that would limit debate on it to 20 hours.