WATCH: Sarah Huckabee Sanders squirms under harsh questioning about GOP attacks on Trump

White House Press Secretary Sarah Huckabee Sanders faced an intense grilling by the White House press corps on Tuesday after President Donald Trump came under heavy criticism from Senators Bob Corker (R-TN) and Jeff Flake (R-AZ).

Politico's White House reporter Matthew Nussbaum asked for the White House to respond to Corker's statement that the president regularly tells untruths and Flake's call on Republicans to end their "complicity and accommodation" of an out-of-control Trump.

Sanders replied that both Corker and Flake are facing steep uphill battles according to polling in their home states and that for them to retire is "probably a good idea."

Fox News' John Roberts asked why the president is wasting time on a "petty feud with Bob Corker" when he should be trying to push through the Republicans' tax plan.

"Look, the president is focused on doing this," Sanders replied, shifting from foot to foot. "That's what he's been spending a good bit of this week doing and that's what he will continue to do until we get the job done?"

Roberts persisted, "But why does he engage like this?"

"He's a fighter," Sanders said of Trump. "And when he gets hit, he's going to hit back."

Maybe Corker is "trying to get a headline or two on his way out the door," she sniped.

She was asked if Trump feels any responsibility for the "breakdown in civility" in the U.S.?

She replied that Corker and Flake are unpopular at home "and I think that shows that the support is more behind this president than it is behind those two individuals."

Watch the video, embedded below: