Indiana House Democrats walked off the floor Monday after losing an effort to put a right-to-work measure aimed at unions before voters, possibly resuming an off-and-on boycott strategy aimed at derailing the measure for the second straight year.

Democrats ended a previous boycott earlier Monday and spent close to five hours debating the right-to-work measure with Republicans. But they left the House floor shortly after losing a party-line vote on the referendum proposal and losing close to a dozen votes to change the measure.

Republican House Speaker Brian Bosma and Democratic House Minority Leader Patrick Bauer quibbled over who was responsible for the renewed tensions. Bauer accused Bosma of cutting debate short before Democrats had finished offering amendments. Bosma accused Democrats of looking for a reason to resume their boycott.

Bauer said Democrats would meet again Tuesday to decide whether to return.

Meanwhile, Senate Republicans had little trouble giving final approval to the right-to-work proposal, which would ban unions from collecting mandatory fees from workers.

The Senate voted 28-22 to send their right-to-work measure to the House.

Republicans, who have a 60-40 majority in the House, had little trouble beating back the series of Democratic proposals to automatically sunset the right-to-work bill if unemployment climbs too high, mandate that the state's economic development corporation disclose terms of business agreements and make other tweaks to the measure.

Lawmakers did approve a pair of Republican amendments to exempt building and construction trade unions from the measure and giving the Department of Labor enforcement authority. The two changes align the House measure with the Senate plan.

Republicans' efforts Monday prefaced what could be a relatively easy final House vote for the right-to-work bill, if Democrats end their boycott.

If the measure is adopted, Indiana would become the first state in more than a decade to approve right-to-work legislation. National advocates have tried without success to push the measure in New Hampshire and other states following a wave of Statehouse victories by Republicans in 2010.

Supporters say the right-to-work measure would bring more jobs to Indiana, where unemployment has crept up to around 9 percent. Opponents say it is aimed at breaking unions and claim it would depress wages for all workers.

Democratic Rep. Scott Pelath of Michigan City opened the lengthy debate Monday with a procedural move designed to kill the measure. Democrats supporting the motion said the legislation is the most divisive bill the Legislature has ever seen.

"This institution is best served if we just end this right here and right now," said Rep. Matt Pierce, D-Indianapolis. "If you look at the collateral damage that this institution has suffered ... you have to ask yourself, at what cost?"

Republican Rep. Jerry Torr of Carmel said the proposal was premature and the GOP-led House rejected the motion, 59-39, as union protesters chanted outside the House chamber.

Republican lawmakers were largely quiet throughout the hours-long debate, rising only occasionally to rebut Democrats. Republican Rep Ralph Foley of Martinsville argued that just because a measure is controversial does not mean it should be avoided.

"I think this is what we do, we don't avoid controversy," Foley said.

Indiana Democrats, who blocked similar legislation with a five-week walkout last year, are seeking a statewide voter referendum in November that would decide the fate of the right-to-work bill. Bauer introduced a version of the referendum on Friday that he said was designed to pass constitutional muster.

Republican leaders maintain that such a referendum isn't allowed under the state constitution and that the Legislature must decide what becomes state law. The Republican-led Senate rejected such a referendum last week.

The right-to-work battle has disrupted the legislative session that began Jan. 4 and has brought large crowds of union protesters to the Statehouse. Bosma last week imposed $1,000-a-day fines against absent Democrats, but a Marion County judge issued an order Thursday blocking those fines from being deducted from the state paychecks of boycotters who have sued.

If the legislation passes, Indiana would become the 23rd state to approve a right-to-work law, handing national conservatives and business groups a major win on an issue that has recently eluded them elsewhere. It also would deal another blow to organized labor, which has seen mixed results in its fight against initiatives to curb union rights nationwide that followed the Republican victories in 2010.

The last state to enact a right-to-work law was Oklahoma in 2001.