COLUMBUS, Ohio -- State lawmakers on Wednesday passed new ballot-access requirements for Ohio's minor political parties, overcoming bipartisan criticism that the changes would block third-party participation in next year's elections.

While the new rules would lower existing thresholds for minor parties to get and stay on the ballot, opponents say the bill is designed to help Gov. John Kasich win re-election by blocking Libertarian Charlie Earl's gubernatorial candidacy.

On Wednesday, Libertarians renewed their pledge to quickly file a lawsuit challenging the changes if they're signed into law.

Under Senate Bill 193, passed by the House and Senate on Wednesday afternoon, third parties would each need to collect about 28,000 signatures, including at least 500 signatures each from at least half of Ohio's 16 congressional districts, to regain recognition as a party by the state.

Minor parties wouldn't be allowed to hold primaries next spring under the proposal. Instead, parties that meet the initial signature requirements by next July would submit to the state a list of candidates to appear on the November ballot.

Starting in 2015, activists would have to collect signatures equal to 1 percent of the last presidential or gubernatorial vote -- about 56,000 votes in the 2012 general election -- to win party recognition. To stay on the ballot, parties would have to garner 3 percent of the vote in a presidential or gubernatorial election.

The revised bill narrowly passed the House 51-43 after the Senate approved it 21-12. The legislation now heads to Gov. Kasich's desk, who must sign it quickly for the new rules to take effect before the Feb. 5, 2014 primary filing deadline.

The thresholds passed in the final bill are higher than those passed by the House last week, though they're lower than those previously passed by the Senate. The legislation went to conference committee after senators noticed that the House's unintentionally deleted some language in its final version of the bill.

State Rep. Matt Huffman, a Republican from Lima, said the thresholds approved Wednesday are a "melding" of the House and Senate versions of the bill.

State Sen. Bill Seitz, the Cincinnati Republican sponsoring the bill, has said the measure is needed to enact new laws to govern minor parties after a 2006 court ruling found the state's previous standards to be unconstitutionally restrictive. Since then, the state has continued to recognize four minor parties: the Libertarians, the Greens, the Constitution Party, and the Socialist Party.

Rep. Jim Buchy, a Greenville Republican, said the new rules make it "very easy"for minor parties to gain and keep recognition.

"What we're doing is we're passing law that will set for all parties what it takes to be on the ballot," Buchy said on the House floor.

Opponents of the legislation have dubbed the bill the "John Kasich Re-Election Protection Act," saying its goal is to prevent Earl from drawing off votes from conservatives disillusioned with Kasich because of his support for Medicaid expansion.

Libertarian State Party Chairman Kevin Knedler said if Gov. Kasich signs the bill on Wednesday, his party would file a lawsuit in either state or federal court by Thursday or Friday. The lawsuit, he told reporters, would challenge the lateness of the legislative changes as well as the abolition of party primaries next year.

Holding a primary, Knedler said, is important for his party because it allows them to build a brand. If the legislation is passed and allowed to stand, he said, it would deal a severe blow to his party's long-term political prospects.

Several House members spoke at length against the proposal before passage.

State Rep. Connie Pillich, a Cincinnati Democrat, called the bill an "atrocity" that would block participation in the democratic process.

"This bill is an attack on democracy," she said.