A Republican former congressman on Thursday claimed that some GOP lawmakers are privately fuming about President Donald Trump's behavior but are sticking with him because the majority of the party's base still supports him.

"I think my former colleagues are in a situation where they understand their base pressure. The base has not yet bolted from the president and I think that's why they're standing with the president for the moment," former Rep. Charlie Dent, R- Penn., told CNN.

"But there's no question having spoken to many of them privately they're absolutely disgusted and exhausted by the president's behavior," he said. "They resent being put in this position all the time."

Dent, who was first elected in 2004 and retired from Congress last year, has been a frequent critic of the administration and the president. His remarks come as the fast-moving impeachment inquiry into Trump has highlighted the deep partisanship in Congress, with Democrats sharply scrutinizing the president's actions and Republicans staunchly defending him.

Dent said that if he were still in Congress he would have voted the move forward with the impeachment inquiry "based on the facts" involving the president allegedly pressuring Ukraine to investigate his political rivals.

Not a single Republican voted to formalize the impeachment inquiry earlier this month, and the lone conservative lawmaker to join the effort, Michigan Rep. Justin Amash, left the GOP in July. Meanwhile, polls continue to show that Republican voters overwhelmingly oppose impeaching the president.

Dent also said he thinks some Republican politicians could speak out as they wrestle with their legacy in office.

"I think a lot of members have to take a hard look at this. They can be more concerned about their election or their legacies. And I would argue to many of them: your legacy is more important than the next election," he said.