After meeting for 19 consecutive weeks — the longest stretch in its 204-year history — the Louisiana Legislature will convene one last time on Thursday as legislative allies of Gov. John Bel Edwards take a final stab at raising taxes to pay for schools, college scholarships and treating the sick.

The key vote will take place on a bill that would raise $88 million by eliminating an income tax break that primarily benefits taxpayers who earn at least $100,000 per year.

Before adjourning by midnight, legislators also must pass a supplemental budget bill to spend the taxes raised during the year’s second special session. How much they authorize in spending depends on whether they pass the tax bill.

A nearly solid wall of opposition from Republicans in the House appears likely to sink the tax bill, which would consist of House Bill 38 amended onto House Bill 50 by the Senate. On Sunday night, the House defeated HB38 on a 47-55 vote. It needed at least 53 votes to pass.

State Rep. Lance Harris, of Alexandria, who heads the House Republican caucus, said he has been checking members almost hourly and hasn’t heard of any of the GOP members shifting from “no” to “yes.” “Nothing has changed on my side,” Harris said in an interview.

If so, it would be a stinging defeat for Edwards, who has pushed hard to secure the necessary six votes.

After the House and Senate quit for the day on Wednesday, after doing little, the Legislature was on target to raise $258 million during the special session, according to the Senate — down from an earlier estimate of $284 million.

An additional $88 million from passing the amended version of HB50 would give state officials $346 million to spend on schools, colleges and universities; prisons; TOPS scholarships; and sheriffs for housing state inmates in local jails.

Either the $258 million or the $346 million is far shy of the $600 million Edwards has been seeking.

The governor has said he will have no choice but to make up any shortfall by cutting popular programs on July 1 when the 2016-17 fiscal year begins.

When Edwards convened the second special session on June 6 — immediately after the regular session, which followed a 25-day special session in February and March — he called on lawmakers to raise the $600 million to maintain funding for the new fiscal year at the current year’s level.

Republicans in the House repeatedly have resisted his call to end individual income and corporate tax breaks, to the frustration of Edwards’ allies.

“We haven’t fixed anything,” state Rep. Sam Jones, D-Franklin, said in an interview. “We’re just plugging holes as we’ve been during the past eight years [when Bobby Jindal was governor].”

But many Republicans say taxpayers have won out.

“It’s a success that we haven’t given government all that it wants,” said state Rep. Cameron Henry, R-Metairie.

HB50 has been passed by the House and is now before the Senate. In its current form, it would raise $13 million by trimming the capital gains tax deduction that benefits the wealthy.

Senate President John Alario, R-Westwego, wants to amend HB50 by adding the language from HB38 onto it, a plan the Senate is certain to approve. The amended version of HB50 then would have to win final approval in the House, which is the sticking point.

The language from HB38 that Alario wants to add to HB50 would no longer allow taxpayers to deduct their previous year’s state and local tax payments on the current year’s state tax return. That change would add an estimated $88 million to the state treasury and thus give the state another $88 million for the programs sought by Edwards and his allies.

The House and Senate did little on Wednesday because Alario, the governor’s most important ally in the Legislature, got word that he has yet to get the votes for the amended version of HB50 in the House. That in turn meant Alario didn’t want the Senate to take a vote in favor of raising taxes by approving the amended bill.

“I’m not going to ask my members to bleed on something that won’t pass the House of Representatives,” he said in an interview.

Thursday will be a strange day in the Capitol. Both the House and Senate convene at 9 a.m., but lawmakers likely will endure long recesses while Edwards and his allies make a last-ditch effort to turn enough Republicans on the amended version of HB50. In the meantime, lawmakers will be working behind the scenes to hash out their differences on several smaller tax bills.

One of the remaining bills — which should pass easily — would restore the sales tax break for a couple of dozen nonprofits that lawmakers inadvertently took away during the first special session. That is House Bill 51.

Lawmakers also must pass the supplemental budget, House Bill 69. Doing that will require resolving spending differences between the two chambers.

The Senate version — passed by the Finance Committee on Wednesday — funds colleges and universities at the amount the governor was seeking. It also provides what state Sen. Eric LaFleur, D-Ville Platte and the panel’s chairman, said he believes will be adequate funding for the state’s medical schools.

The Senate panel got the funds for the colleges and universities and the medical schools by taking $21 million away from K-12 schools.

The Senate Finance Committee plan keeps funding for the popular Taylor Opportunity Program for Students at about 70 percent, as was provided when HB69 left the House floor earlier this week. Funding only 70 percent of each scholarship likely will mean LSU students would have to pay an additional $2,100 next year to make up the difference, said Jason Droddy, a university official.

Even as some eyed additional dollars, the Senate Finance Committee discovered that it has even less money to work with than the House version of the budget included.

The House had calculated about $24 million that already had been spent in the nearly $26 billion budget bill approved during the regular session, according to the Senate — a view not shared by House leaders.

Mark Ballard, of The Advocate Capitol news bureau, contributed to this report. Follow Tyler Bridges on Twitter, @TegBridges. Follow Elizabeth Crisp on Twitter, @elizabethcrisp.