Almost 51,000 Ohioans in the state’s six largest counties voted during the first 15 days of early voting for the presidential election, a period that the Ohio House voted to trim out of Ohio law on Tuesday.

That number represented 22 percent of about 227,000 people who took advantage of early voting in Cuyahoga, Franklin, Hamilton, Montgomery, Summit and Lucas counties, according to county figures compiled by the Associated Press. The remainder voted during the final 20 days of early voting, which will remain in place under the House plan.

The Republican-led House voted 54-42 along mostly party lines on a bill shrinking the newly instituted early voting period that drew long lines of voters for this year’s election. It now heads back to the state Senate, which will decide whether to go along with the changes made by the House.

The proposal reduces the start of in-person early voting from 35 days before Election Day to 20 days. It also eliminates a window during which voters could both register and vote on the same day.

Republicans pushed the bill over the objections of Democrats and some elections experts, who accused the GOP of ramming through changes without understanding the consequences. This is the final week during which Republicans control both chambers of the state legislature, after having lost control of the House to Democrats in the Nov. 4 election. The new legislature will be seated in January.

‘‘The two consistent messages, in both written and in personal testimony, were that election reform should be comprehensive, deliberate, well thought out and it should not be rushed, and two, it should be bipartisan,’’ said state Rep. Dan Stewart, a Columbus Democrat. ‘‘(This) fails both those criteria.’’

Statewide data breaking down how many voters took advantage of each day of early voting before the Nov. 4 election has not been compiled by the state. Some of Ohio’s 88 counties told the AP on Tuesday that officials did not keep daily totals, so the break down may never be known.

About 1.5 million people voted during the 35-day early voting period this fall. Lawmakers who support the bill say they don’t know how many fewer people would cast ballots by shrinking the window. Early voting was credited with helping reduce some of the long lines that had plagued Ohio polls in the 2004 presidential election.

The legislation’s GOP backers said they pursued the changes to the election calendar primarily to get rid of a weeklong period in which voters could both register and cast a ballot on the same day.

‘‘We were focused on those issues that the secretary herself said were unclear from her point of view,’’ said House Speaker Jon Husted, a Kettering Republican.

In trying to sell the bill to skeptical Democrats, Republicans have said their proposal is narrowly tailored to address points of confusion that came up before the election, such as the same-day registration and voting period.

Republicans also argued the so-called ‘‘Golden Week’’ invited fraud because officials lacked time or information to verify registration information before the new voter’s ballot was cast.

That window existed for years as a result of the overlap between the beginning of absentee voting and the end of the registration period, which is 30 days before Election Day. It did not become controversial until in-person absentee voting, new in recent years, was encouraged by Democratic presidential nominee Barack Obama.

The highest percentage of early voting in the first 15 days was in Franklin County, where Obama held rallies in downtown Columbus.

Secretary of State Jennifer Brunner has said she’s not opposed to eliminating the window and would be OK with decreasing the early voting period. But Brunner and Democrats have said that a lame-duck legislative session isn’t the proper time to rush through elections changes.

Gov. Ted Strickland, a Democrat, has not yet said whether he will veto the bill, but has said he has concerns about the legislature moving head with the changes during this session.

Ohio election watchers are still working to compile data on how many, if any, cases of fraud from the fall election were referred to prosecutors, said Ohio Citizen Action’s Catherine Turcer. The information was not included in separate analyses of the bill compiled by legislative analysts and by Brunner.

The proposal also allows partisan election observers to be present during early voting, and requires the secretary of state to share with boards of elections the names of voters whose registration information doesn’t match data in government databases. Both of the changes are responses to lawsuits that Republicans brought against Brunner in the days and weeks before the election.

House Republicans also amended the bill to address another controversial topic — the secretary of state’s power to control the appointments of members to Ohio’s local bipartisan elections boards.

The amendment requires the state’s top elections official to have a good reason to reject a board appointment. Republicans were furious when Brunner rejected a Republican recommendation for appointment to the Summit County Board of Elections. Her decision was later overturned by the Ohio Supreme Court.