AUGUSTA — About a week after it passed the Senate, but with less than the two-thirds support needed to muscle past a certain gubernatorial veto, the Maine House of Representatives on Tuesday will consider a bill aimed at expanding Medicaid to more than 70,000 low-income Mainers as part of the federal Affordable Care Act.

The bill represents a proposal by moderate Republican Sens. Roger Katz of Augusta and Tom Saviello of Wilton. It combines Medicaid expansion, which has been the Democrats’ top legislative priority for two years, with a plan to mandate big savings by outsourcing the publicly funded health insurance program to managed care organizations.

On paper, the bill addresses all the concerns Republican opponents of expansion have raised for two years: The expansion lasts only as long as the federal government pays for nearly 100 percent of the cost, and it would require a vote of the Legislature to continue beyond that. It also includes an automatic opt-out if federal funding drops below promised levels. The Legislature’s nonpartisan budget analysts say the cost of the proposal is minimal.

It also uses built-in savings to clear our a waiting list of Medicaid recipients awaiting in-home and community services, which opponents have said need to be addressed before the program is expanded to include all of Maine’s poorest residents.

Still, the bill has struggled to gain Republican support. In the Senate, Katz and Saviello were the only members of their caucus to support the bill. Even Sen. Patrick Flood, R-Winthrop, who voted for Medicaid expansion last year, opposed the measure.

The bill passed the Senate, 22-13, enough to advance the bill to the House, but not enough to override a certain veto by Gov. Paul LePage, one of the plan’s fiercest critics.

Meanwhile, House Republicans have pivoted to new talking points, emphasizing that roughly two-thirds of the expansion population is already eligible for subsidized private health insurance plans through online exchanges as part of the Affordable Care Act. Still, the poorest one-third of the population is not eligible for subsidies and, without expansion, is also not eligible for Medicaid.

Democrats are quick to point out that choosing not to expand leaves the most needy without options.

House Speaker Mark Eves, D-North Berwick, said Democrats will make their case on the House floor, telling the stories of sick, needy Mainers who stand to benefit from Medicaid expansion and of the economic boom predicted by the massive influx of federal dollars into the state.

“Who knows how the vote is going to shake out?” he said in an interview Monday. “But we certainly know we stand tall and proud knowing that we’re fighting for the right thing for our people and our economy.”

Meanwhile, House Republicans say momentum has swung in their direction and are bullish on their ability to defeat the Democrats’ top legislative priority: “It’s looking like enough lawmakers now understand the disastrous consequences of ObamaCare’s welfare expansion, but we’re not taking anything for granted and will be making a strong argument on the House floor,” said House Minority Leader Ken Fredette, R-Newport, in a prepared statement on Monday.

The House opens session at 9 a.m., and debate on Medicaid expansion is expected to last several hours. House sessions are broadcast live on the Maine Legislature’s website, here.