Republican Rep. Charlie Dent said Sunday the GOP is "alienating" voters by running candidates that appeal to small swath of the electorate.

"I mean, we can't run these candidates who appeal to a very narrow base. I mean this Roy Moore candidacy even before the very serious allegations of sexual misconduct, this man was unfit," the Pennsylvania Republican told ABC's Mary Bruce on "This Week."

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A self-styled moderate, Dent was the leader of the House's Tuesday group, a cadre of Republicans that is relatively liberal compared to the House Freedom Caucus or Republican Study Committee. Dent and the group played a major role in Republican efforts to repeal and replace the Affordable Care Act, which eventually passed the House but failed in the Senate.

The Pennsylvania Republican added the heart of the problem is the GOP primary process.

"Our primary process leads to the candidates who tack to the fringe or tack to the to the base," he said. "And I think we've seen too much of that, there’s too much political reward for tacking really hard to the base and not enough reward for consensus and agreement, or heaven forbid, compromise."

While Dent is retiring, he said that the process could improve in 2018. But he's certain that Republicans will experience losses in the midterm elections and that he has told his colleagues to be prepared for a "really tough year."

"I've told my colleagues, look we're going to be running into a headwind, you better be prepared for the worst and hope for the best."

Dent, who was first elected in 2004 in a swing district in Northeastern Pennsylvania, said one of his reasons for retiring is that Washington is paralyzed by gridlock — and was even before President Donald Trump was elected.

"The simple basic tasks of government have become Herculean tasks," Dent said Sunday. "There are too many people here who've taken saying no to an art form, a lot of people here just can't get to yes."