WASHINGTON -- The head of the group tasked with defending and expanding the GOP's majority in the U.S. House said the impact of anti-establishment presidential candidates such as Donald Trump on congressional races is still unclear.

But U.S. Rep. Greg Walden, the chairman of the National Republican Congressional Committee, noted the anger that's been demonstrated on the presidential trail has yet to evict any House incumbents so far.

"Even with these elevated turnouts, nobody's losing their primaries," the Oregon Republican said at a roundtable with a small group of reporters Friday. "So if it was a 'throw 'em all out' (year), we would have seen some of that occur and we're not seeing that occur. Nor do we even see a lot of evidence of tight primaries."

Walden pointed out that at roughly this time in 2014, senior lawmakers Eric Cantor of Virginia, at the time the House majority leader, and Ralph Hall of Texas had lost their primaries.

Walden attributed part of the phenomenon to the fact that this year voters can focus their dissatisfaction on the presidential contest, unlike 2010 and 2014 when the only outlet was the congressional races. He added that more of a presence at home has helped shield incumbents from much of the anti-Washington rhetoric that's dominated the White House race.

That rapport, however, has not been enough to stop many incumbents from Georgia's deep-red congressional districts from feeling the heat this year for past votes deemed too pro-establishment or insufficiently conservative.

Many Democrats are banking that a November ballot with Trump -- or, to a lesser extent, Ted Cruz -- at the top could put states like Georgia in play for the party this year by pushing some Republicans to sit out and bringing Democratic constituencies such as minorities and women to the polls. But Walden said the NRCC is waiting until after the conventions before making any major bets on House races based on the remaining presidential candidates.