Republican senator slams proposal to again separate families at border: It 'simply is un-American' Sen. Flake responded to report that family separations at the border may resume.

A leading Republican critic of President Donald Trump slammed a reported proposal for the U.S. to resume separating migrant and refugee families at the U.S. border, saying such a policy "simply is un-American."

Sen. Jeff Flake, R-Ariz., responded to a question from ABC News Chief Anchor George Stephanopoulos on "This Week" Sunday about a report that the White House is weighing a new effort to separate families at the border in hopes of reducing the number of people trying to enter the country illegally.

The president on Saturday commented on the proposal, which was first reported by The Washington Post. "If they feel there will be separation, they don't come," Trump said.

Stephanopoulos asked Flake about the timing considering that a new ABC News/Washington Post poll shows Democrats have a big edge over Republicans on who voters trust to handle immigration.

"Is the president making a mistake here?" Stephanopoulos said.

Flake responded, "Yes, he is. We shouldn’t bring that policy back. That, that simply is un-American, and I think everybody recognized that. The president seemed to. Certainly the first lady and others spoke directly against it."

In an exclusive interview with ABC's Tom Llamas last week, first lady Melania Trump said the administration's earlier family separation policy was "unacceptable."

"It was unacceptable for me to see children and parents separated," the first lady said. "It was heartbreaking. And I reacted with my own voice."

With midterm elections approaching in just over three weeks, Flake said in an interview with C-SPAN this week that he hopes somebody runs against Trump in the Republican primary in 2020.

Stephanopoulos asked Flake if he agrees with commentator George Will's call for conservatives to vote for Democrats in the midterms as a check on Trump.

The Arizona senator, who will leave office in January after choosing not to run for re-election, said he hopes Republicans can be a check on the president while still holding a majority in Congress.

"I think that Republicans need to provide that check, and that's what our system of government does, and I hope that they can without a change in who controls Congress," Flake said. "But I think that that may be coming if you believe the conventional wisdom, and I kind of do: The House will likely flip [to Democratic control]; the Senate will remain in Republican hands."

Flake also commented on the public's view of the confirmation of now-Justice Brett Kavanaugh. According to the new ABC News/Washington Post poll released Sunday, a majority of Americans believe that the Senate Judiciary Committee did not do enough to investigate the claims made by Christine Blasey Ford, who accused Kavanaugh of sexual assault when they were teenagers.The poll also found that a majority of Americans want more congressional inquiry into Kavanaugh.

Flake, a Judiciary Committee member, had demanded an investigation of allegations that arose during the confirmation process of sexual assault and sexual misconduct by Kavanaugh during high school and college. After the FBI conducted a supplemental background investigation of the nominee, Flake joined the Senate majority in approving Kavanaugh for the Supreme Court.

"I know a lot of people wanted [the supplemental investigation] to be more broad," Flake said. "I would have liked to have started it earlier and had it more broad, but it was a good investigation. And I think we’re in a better place than we would have been" without the additional investigation.

Flake added that he doesn't think Congress should hold any additional investigations into Kavanaugh or into how Ford's allegation became public.

Ford's said he had that while the confirmation was an "awful process," he doesn't believe that Congress should conduct any further investigations to Kavanaugh nor the leak of Christine Blasey Ford's letter.

"I don't think that we should move forward, the Congress certainly, with additional investigations," he said.