WASHINGTON — (TNS) Senate negotiators sounded doubtful they could put forward a bipartisan immigration proposal before Congress leaves Washington for an August break, dimming the prospects to pass long-awaited immigration changes ahead of midterm elections that could flip control of Congress.

North Carolina Republican Sen. Thom Tillis, one of the four senators meeting regularly to discuss bipartisan immigration bills, said this week that the group is “not going to have the capacity to have anything put down before we return from the August recess.”

“It’s just that we’re down to effectively four weeks — four-and-a-half weeks of chamber time — and a lot of things that are already planned to be slotted in,” Tillis said Wednesday.

Sen. Bob Menendez, a vocal proponent of legislation to legalize undocumented immigrants, was also pessimistic Wednesday that any immigration bills could move before recess.

The New Jersey Democrat said he is “not aware of any progress of any consequence made by” the immigration group, which also includes Senate Judiciary Chairman Richard J. Durbin, D-Ill., and Sens. Alex Padilla, D-Calif., and John Cornyn, R-Texas.

Menendez also said he doesn’t see any must-pass bills over the summer to which senators could attach immigration changes.

“I’m not expecting to see too much,” Menendez said. “I don’t see any legislative vehicles that can be used at this time, that are must-pass, that will take place during this period of time.”

The fizzling efforts follow a more than yearlong push by immigrant advocates, while Democrats hold majorities in both chambers of Congress, to advance legislation to shore up the legal immigration system and provide a path to citizenship for millions of immigrants without legal status.

Last year, Senate Democrats attempted to include provisions to create a citizenship path into the party’s sprawling social and climate spending package. They were ultimately thwarted by internal party divisions and chamber rules.

The bipartisan group of four began meeting earlier this year in a stated effort to identify smaller, more narrow immigration bills that could garner the needed 60 votes to move forward in the evenly divided Senate.

But initial meetings have continued to focus on border security and asylum processing.

“We’re trying to get that piece done, and then we’re talking about other elements of the immigration components,” Tillis said. “Right now it’s been focused on border security.”

Durbin said Wednesday that the group is “dealing with the southern border as well as a long list of opportunities for immigration in this country.”

Meanwhile, the ongoing negotiations on border processing have prevented other immigration bills from moving forward.

One such proposal to revise the agricultural visa system and allow some migrant farmworkers to apply for green cards passed the House last year with more than two dozen Republican votes, but a Senate version has yet to be introduced.

Sen. Michael D. Crapo, R-Idaho, who has been negotiating a Senate version with Colorado Democratic Sen. Michael Bennet, on Wednesday said these efforts are “still stalled” by the group of four’s ongoing “negotiations over the border issues.”

The Senate Democrats in the negotiations, while acknowledging the challenges associated with immigration legislation over the next few months, weren’t yet ready to throw in the towel.

Durbin said Wednesday that it “is a challenge, but I think there is a chance” to see immigration action from Congress before recess.

Padilla said the talks continue, “so always be hopeful.”

If Congress fails to pass immigration legislation this year, the result of this fall’s midterm elections could determine prospects for action over the next two years.

Republicans are well positioned to win the majority in the House and predicted to get a net gain of one seat needed for control of the Senate, according to CQ Roll Call elections analyst Nathan L. Gonzales.

Republicans have historically opposed legislation to help undocumented immigrants obtain green cards without measures ramping up border security, causing a decadeslong stalemate on the issue.

Menendez said it will depend on whether senators who are elected are willing to work on immigration policy.

“If it doesn’t happen this year, it will depend upon the results of the election,” Menendez said. “Do we have more people who are willing to deal with solving a broken immigration system, or do we have more people of the Trump mentality in which nothing can be done?”

Tillis said the group plans to continue meetings to discuss immigration bills in the fall ahead of the elections. “It’s a building process,” Tillis said.