Conservative opposition put a House Republican gun and anti-terrorism bill in jeopardy Wednesday, even as Democrats pressed for election-year votes on their proposals to stiffen firearm curbs.

In an embarrassing blow to House Speaker Paul Ryan, members of the conservative House Freedom Caucus said they would oppose the measure despite its similarity to a GOP bill in the Senate that's endorsed by the National Rifle Association.

Caucus members complained that the House bill, which Ryan has been pushing, did not adequately protect the rights of gun owners.

In a written statement, the Freedom Caucus, which claims about 40 House members, also faulted the measure for "failing to do enough to address the threat of radical Islamic terrorism."

Without their support and with solid Democratic opposition, Republicans would lack the votes to move the bill ahead.

Ryan, R-Wis., told reporters, "We're going to get it right and we're going to do it when we're ready."

Conservative upheaval against Ryan has been less frequent and vitriolic than it was against his predecessor as speaker, John Boehner, R-Ohio, whose retirement was hastened by the conservatives.

Even so, their opposition comes on an issue that's been catapulted back into prominence by last month's mass shooting in Orlando, Florida, and Ryan would like to demonstrate that the GOP can act.

Underscoring the pressure on GOP leaders, a vote on the Republican measure would be a departure: Since the 2012 slaying of school children in Newtown, Connecticut, Republicans have not brought any legislation broadly restricting guns to the House floor.

The party turmoil endangered a measure that has become a partisan battlefield over gun control and terrorism. Two weeks after staging a House floor sit-in to dramatize their demands, Democrats are pressing for votes on two amendments. One would broaden background checks for gun buyers, and the other would ban many firearms sales to suspected terrorists.

Ryan has so far turned aside the Democrats' demands for votes.

At a rally on the Capitol steps, House Democratic leader Nancy Pelosi of California said Democrats want "real action, not a bill written by the gun lobby." She added: "The Republican House still refuses to disarm hate."

"We don't know what form it's going to take, but stay tuned, stay tuned," Rep. John Lewis, D-Ga., a leader of last month's House sit-in, said at the rally about future Democratic actions.

At least for now, Democrats are allowing the House to conduct regular legislative business without disruptions. They indicated they would support a compromise bill Wednesday strengthening mental health programs.

Ryan spokeswoman AshLee Strong said the two parties "have different views on how to achieve a shared goal of preventing gun deaths," especially over protecting gun owners' rights. She said the next steps on anti-terror legislation "will be discussed and determined by the majority in the coming days."

Republicans, backed by the NRA, seem intent on preventing any limitations on the constitutional right to bear arms, which they say the Democratic measures would impose. They also said they were investigating Democrats' behavior during the sit-in, including whether they intimidated House aides and damaged furniture.

The GOP bill would bar many gun sales to suspected terrorists, but only if federal prosecutors could prove within three days that a terrorist act was afoot. The government would have to cover legal costs for people for whom it unsuccessfully tried to deny firearms.

Republicans say their measure protects peoples' constitutional right to legal protections. Democrats say it sets an untenably difficult hurdle that makes the whole proposal unworkable.

That bill would establish an office within the Department of Homeland Security to focus on what the measure calls "radical Islamist terrorism" within the U.S., and set up modest grants for communities trying to counter such threats.