For two straight sessions, House Speaker Richard Corcoran has controlled the legislative agenda and passed anything he wanted — until Parkland.

As the Legislature's elaborate but hurried response to the massacre heads to the full House, opposition is growing. The House bill (HB 7101) is in serious trouble as members of both parties keep finding reasons to vote against it.

What began as a bipartisan consensus in a House committee has collapsed as Florida deals with its worst crisis over gun violence and legislators confront the political risks of a single vote in an election year.

Corcoran is a leading supporter of school marshals, or arming trained teachers and staffers. He calls the bill a "game changer … a giant step forward in school safety."

House GOP leaders rallied around him, but the idea is very controversial. Some Parkland parents call it reckless. A new Quinnipiac poll says 56 percent of Florida voters oppose it.

Corcoran went on Fox News to amplify his message and his PAC sent out an email noting that President Trump likes the idea, suggesting that the speaker, a possible candidate for governor, sees a political dividend.

But he faces a revolt on multiple fronts:

* Pro-gun hard-line Republicans oppose a three-day waiting period to buy a gun and raising the purchase age to 21. They include Rep. Blaise Ingoglia, chairman of the Florida GOP, and Jay Fant, one of three House GOP members running for attorney general.

* Some Democrats will vote no because the bill doesn't go far enough by outlawing weapons like the AR-15-style rifle used at Marjory Stoneman Douglas High School. The Quinnipiac poll shows 62 percent of Florida voters support a nationwide ban on assault weapons.

* Gov. Rick Scott opposes arming teachers. His Republican allies in the House can cite that alone in voting no.

* The Legislature's black caucus met Wednesday and opposed the bill, in part out of concern that arming school personnel could encourage racial profiling.

Sen. Perry Thurston, D-Fort Lauderdale, said he and fellow black caucus members will demand an assault weapons ban. "That's what Connecticut did" after the Sandy Hook massacre, he said.

A very unusual coalition of pro-NRA Republicans, liberal anti-NRA Democrats, Scott loyalists and African-Americans could be enough to defeat the bill.

"The politics around this are toxic," said Rep.  Jose Oliva, R-Miami Lakes, a key Corcoran ally.

Corcoran needs 59 votes to pass a bill in the 117-member House, with three seats vacant.

There are 76 Republicans and 41 Democrats, and the fact that the outcome of a bill is in doubt with an overwhelming GOP majority shows the level of volatility over guns in Tallahassee.

Asked if he has the votes, Corcoran did not predict victory. He told the Times/Herald: "When you have a crisis like this … I find it hard to believe that the House, Senate and the governor can't come to an agreement and have the votes to pass it."

Republicans who reliably support Corcoran declared themselves undecided Wednesday — another ominous sign.

Rep. Tom Goodson of Rockledge said he hasn't made up his mind, and that getting the votes is "a problem" because of the age 21 restriction. Rep. Clay Yarborough of Jacksonville said House leaders sought him out two or three times, and he told them: "I'm officially undecided."

If Democrats take a united stand against the measure, the bill's fate will be decided by a family feud between Republicans, fighting over guns.

Corcoran could remove the marshals program, but that would look like he's capitulating to Democrats. If he takes out the waiting period or age limit, he will antagonize senators and will be vilified for caving to the NRA.

"The bill is not in a safe spot right now," said Rep. Evan Jenne, D-Dania Beach, the House Democrats' policy chief. "If enough Republicans stick with (NRA lobbyist) Marion Hammer, it's done for."

— With reporting by Mary Ellen Klas, Elizabeth Koh and Lawrence Mower.