ST. PAUL — The Minnesota House passed a bill Monday establishing the state’s health insurance exchange, the first step toward enactment of an online marketplace that aims to give more than a million Minnesotans a new place to purchase affordable health insurance.

Rep. Joe Atkins, the chief House sponsor, called the bill creating a health insurance exchange “the most significant health reform in 50 years” — since Medicare and Medicaid were created in 1965. The exchanges are a centerpiece of the federal health care overhaul.

Preliminary estimates are for the Minnesota-run exchange to offer coverage to 1.3 million people. Of those, about 300,000 currently lack health insurance.

“That’s people who will have insurance to rely upon to cover their health care needs,” said Atkins, DFL-Inver Grove Heights.

Another 600,000 are people currently covered by public programs, and several more hundred thousand are small employers who ideally will be able to get a better deal than their current insurance offers.

The House approved the bill 72-58 on a nearly party-line vote, after a debate that lasted more than five hours. One Republican and one Democrat crossed party lines: Rep. Jim Abeler, R-Anoka, supported the bill, while Rep. Laurie Halvorsen, DFL-Eagan, voted against it.

The debate also produced a brief skirmish over abortion. The House amended the bill to prohibit abortions from being covered in plans sold on the exchange, with a handful of Democrats joining Republicans to make the change. A DFL lawmaker pointed out that the federal health care law also prohibits abortions from being covered.

Republicans complained that lawmakers were investing major state resources and time in an experiment. They raised concerns the exchange would drive insurance costs up for many Minnesotans, that participants would lose access to favorite doctors and that private medical information might not be closely guarded.

“Welcome to the Democrats’ health care exchange: less choice, more cost, no privacy,” said Rep. Kelby Woodard, R-Belle Plaine.

But Atkins said the average annual savings in health premiums for participants is projected to be $490. Some will save more while others earn too much money to qualify for tax credits for participants under certain income levels.

“Even the cheapest one will be a dramatic improvement over what most people in Minnesota currently have,” Atkins said, explaining that provider networks would be bigger and deductions and co-pays smaller. He said the website would be like sites where travelers compare and purchase plane tickets or hotel reservations, offering a range of insurance policies for consumers to choose from after they’ve entered personal information.

The exchange will be governed by seven people appointed by the governor and subject to approval by the House and Senate. Its expected operating costs of $60 million a year would be covered with a fee on premiums of up to 3.5 percent. That’s a key difference with the state Senate’s health care exchange bill, which instead taps money from a state tobacco tax.

The Senate bill is due for a floor debate and vote on Thursday. Differences will be reconciled in a House-Senate conference committee, and lawmakers are on a tight timetable: A federal deadline requires the bill to be passed by the end of March, with enrollment due to start on Oct. 1.

Under the federal law, states had a choice of creating their own insurance exchanges or leaving the job to the federal government. Atkins said Minnesota’s legacy of innovative health policy was incentive to design the state’s exchange here instead of Washington.

A series of changes sought by Republicans in the House minority were mostly unsuccessful. Republicans tried but failed to make the exchange board’s seats elected rather than appointed, to force the exchange’s managers to obtain their own insurance through it, and to strip money from the bill for marketing of the exchange.

“For some of you this will be one of the biggest bills of your career,” said Abeler, who voted for the bill in order to secure a spot on the conference committee where he said he hoped to improve the measure. “We could be looking back and saying, ‘What did we do? We took away people’s choices.’ It’s a great peril — this thing has to work in real life.”

Some of Atkins’ fellow House Democrats were unhappy with a late change to the bill, one that he pushed as an effort to entice insurers to participate. It would give those insurers the chance to sell some of their specific products in the new marketplace. That provision is not in the Senate bill.

Gov. Mark Dayton, whose administration has worked to help implement the exchange, acknowledged the risk involved.

“It’s a big gamble,” Dayton said during a Minnesota Public Radio call-in show. He added, “I’m sure there are going to be glitches. There has to be glitches with something of this enormity.”