Senators are ramping up their efforts to block President Trump's emergency arms sales to Saudi Arabia and other Gulf allies.

Lawmakers in both parties are feeling a sense of urgency to respond to Trump's use of executive powers before the weapons are delivered to Riyadh and after he flirted with declaring yet another emergency, this time for tariffs on Mexican goods.

During the past week, senators introduced 22 resolutions - one for each sale - that would block the deals, an unprecedented congressional move following White House approval of emergency arms sales.

Sen. Lindsey Graham (R-S.C.), a staunch Trump ally, is among those supporting the resolutions. And senators say that his backing best illustrates the level of frustration on Capitol Hill.

"The fact that Lindsey is leading the resolution tells you that things are shifting inside the Republican caucus," said Sen. Chris Murphy (D-Conn.), one of the co-sponsors. "I've offered two prior disapproval motions on Saudi arms sales, and Lindsey led the opposition to my prior attempts to stop Saudi arms sales."

Asked about growing frustration among Republicans, Graham said, "I think there'll be a lot of support" for the resolutions.

Late last month, the Trump administration notified Congress it was invoking a rarely used provision of the law governing arms sales to push through long-stalled deals with Saudi Arabia and the United Arab Emirates (UAE) worth $8.1 billion.

A provision of the Arms Export Control Act allows such sales to go through immediately without a 30-day congressional review period in cases deemed an emergency.

The Trump administration cited alleged threats from Iran to justify the emergency provision.

The Defense Security Cooperation Agency initially released details for only seven of the sales on the day of the notification. The rest were published this past week in the Congressional Record.

For Saudi Arabia, the sales include F-15 fighter jet support, Paveway precision guided munitions, aircraft maintenance support, mortar rounds, engines for F-15s, and logistics and support for Saudi spy planes.

Additionally, as first reported Friday by The New York Times, the Raytheon-made Paveway smart bombs will be co-manufactured in Saudi Arabia - raising concerns that doing so could give the Saudis access to technology to produce their own version of the bombs.

For the UAE, the sales include helicopter equipment, laser-guided rockets, anti-tank missiles, Paveway smart bombs, Maverick missile support, drones, .50-caliber rifles, Patriot missiles, U.S. Marine Corps training of the UAE Presidential Guard and F-16 engine parts.

The UAE was also approved to provide some of the Paveway bombs to Jordan.

Lawmakers had been holding up the sales amid concerns about civilian casualties in the Saudi-led war in Yemen and fury at Saudi Arabia over its killing of U.S.-based journalist Jamal Khashoggi in Turkey last year.

The senators seeking to block the sales are confident they have enough support to pass all 22 resolutions.

"First time we had a vote, we got about 22 people to oppose the sale. Last time, I think we got nearly 50," said Sen. Rand Paul (R-Ky.), a co-sponsor. "I think there's a growing number of people and a growing resistance to allowing the government to operate by emergency. And so I think that you're going to see the biggest vote we've had, and it may well be a significant majority of the Senate is going to resist allowing the president to sell arms without our approval."

Fueled by the same concerns factoring in now, a March resolution to end U.S. military support for the Saudi-led coalition in Yemen passed the Senate in a 54-46 vote.

Still, efforts to block the sales face several hurdles on Capitol Hill. For one, it is unclear whether senators will be able to force votes on their resolutions.

Under normal procedures, the Arms Export Control Act says a resolution of disapproval is privileged, meaning senators can force a vote on it. But lawmakers have never tried to pass a resolution of disapproval after a president has invoked the emergency provision.

Sen. Bob Menendez (D-N.J.), the ranking member on the Senate Foreign Relations Committee, said Wednesday that he and other sponsors believe they can force a vote on their resolutions. They are in conversations with the Senate parliamentarian to see if that's the case.

A Senate staffer told The Hill on Friday that a ruling from the parliamentarian likely won't come until the measures are called up on the chamber floor.

If the parliamentarian rules in their favor, supporters will need a simple majority to send the resolutions to the Democratic-controlled House.

They would later need at least 67 votes to override Trump's likely veto. Republicans hold a 53-47 majority in the Senate.

"We've already got three Republicans as co-sponsors. There's one more who's considering it. That would give us 51 votes," Menendez said. "Veto-proof, that's another story."

Murphy argued that opposition to the arms sales is growing because Saudi Crown Prince Mohammed bin Salman "going off the rails is now hard for the Saudis to disguise."

"So, we'll see," Murphy said on Republican support for the resolutions of disapproval. "Sen. [Marco] Rubio [R-Fla.] has made clear his distaste for the Saudi regime. Will he join he join us in supporting the resolution? If people like Sen. Rubio join us, then all of a sudden, we're getting close to 67 votes."

Rubio would not say how he would vote on the resolutions, adding that he hasn't read all 22 of them. But he said that in general he does not support the arms sales.

"Even though I may support the sale of defensive weaponry, I don't support the administration going around the existent congressional review process and the prerogatives that have always been respected when it comes to the chairman and the ranking member" of the Foreign Relations Committee, he said.

Meanwhile, Foreign Relations Committee Chairman Jim Risch (R-Idaho) is trying to balance increasingly restless committee members with his support for Trump. Risch said he is still working on a broader bill to address several issues related to Saudi Arabia that could get Trump's signature.

Risch said it would not be "appropriate" to say whether he supports the arms sale resolutions until that broader measure is finalized.

"Right now, those are being negotiated along with the overall Saudi Arabia bill, and I think support or nonsupport is not appropriate until we get to a global deal," Risch said.

"It's a long-term relationship," he added of U.S.-Saudi relations. "It's been a complicated relationship, but there's things that happened over the last year and recent years that cause all of us to need to recalibrate."