“Despite our repeated calls, the Biden administration failed to plan ahead and implement a realistic, workable plan; our legislation gives them more time to put a plan in place that will secure our border, protect Arizona communities on the frontlines of this crisis, and ensure migrants are treated fairly and humanely,” Sinema said in a statement.

The legislation would provide protections for migrants whose return to their home countries would threaten their life, freedom, or expose them to torture. It also provides protections for migrants with acute medical needs.

Sens. Joe Manchin (D-W.Va.) and John Cornyn (R-Texas) are also co-sponsoring the bill.

The legislation would need at least 60 votes to pass the Senate, making it all but guaranteed that it won’t pass before Title 42’s expiration, and it faces an uphill climb more broadly in a chamber that has struggled in recent years to find consensus on border and immigration issues.

And it comes as the House is set to vote on its own sweeping border and immigration proposal next week. But it’s not meant to be a response to that bill — with aides and senators involved noting that Sinema, Tillis and others are holding broader talks on a separate track — but instead is in response to the looming May 11 date for the expiration of the Trump-era authority.

The end of Title 42 has sparked fierce criticism from Republicans, as well as warnings from some Democrats who worry that the administration doesn’t have the resources positioned along the U.S.-Mexico border to be able to process an increase in migrants seeking entry into the United States.

Eleven Senate Republicans — including Minority Leader Mitch McConnell (R-Ky.) and Sen. Lindsey Graham (R-S.C.) — sent a letter to Biden Wednesday urging him to reverse course and keep Title 42 in place. Graham, in a press conference on Wednesday, compared the end of Title 42 to “being hit by a slow moving truck in Kansas.”

“I’m asking them to find an acceptable substitute for Title 42,” he added.

The administration had initially planned to end the Trump-era program on May 23, 2022. But the policy got tied up in a lengthy court battle as Republicans made an effort to keep the authority in place. The Biden administration then announced in February that the end of the Covid-19 pandemic public health emergency would also terminate Title 42.

But the issue is rife with potential political trip wires for the Biden administration, who faced public urging from Democrats over the past year to keep the program in place. Tillis and Sinema offered an amendment late last year that, among other provisions, would have extended Title 42 and boosted border funding. The proposal failed but got support from several senators up for reelection in 2024 in red and purple states: Sens. Sinema, Jon Tester (D-Mont.), Jacky Rosen (D-Nev.), Sherrod Brown (D-Ohio) and Manchin.

Asked whether he would support a two-year expulsion authority similar to Title 42, Sen. Mark Kelly (D-Ariz.) told reporters on Thursday that he’s instead been “working on getting the resources” border officials need if Title 42 goes away.

“We’re looking at other options. Right now I’ve been focused on getting the resources they need for when May 11 comes,” said Kelly, who previously voted for the duo’s amendment last year.

Manchin, who like Sinema hasn’t yet announced if he will run for reelection, called the end of Title 42 a “shame” and appeared frustrated by Congress’ inability to legislate on the border.

“I think the border has to be secure, period. … It’s a disaster at the border,” Manchin said in a brief interview, asked about steps the administration or lawmakers should take.

The administration has been ramping up its response to the policy ending as they face concerns about being able to respond to a potential increase sparked by both the end of Title 42 and the upcoming summer season.

The administration announced late last month that it would establish immigration processing centers throughout Latin America to help slow down the number of migrants coming to the U.S.

And earlier this week the administration announced it would add another 1,500 active-duty troops to the southern border to deal with the influx of migrants expected with the expiration of Title 42.

The additional troops, which are being sent to fill a request from the Department of Homeland Security, will fill “critical capability gaps,” including detection and monitoring, data entry and warehouse support. They will be there for up to 90 days, after which military reservists or contractors will do the work.