Yuri Gripas / Reuters Sen. Susan Collins (R-Maine) says Donald Trump "does not reflect historical Republican values, nor the inclusive approach to governing that is critical to healing the divisions in our country."

Sen. Susan Collins (R-Maine) just joined a small but growing list of Republican members of Congress who won’t vote for GOP presidential nominee Donald Trump come November because of his temperament and rhetoric.

“Donald Trump does not reflect historical Republican values, nor the inclusive approach to governing that is critical to healing the divisions in our country,” Collins wrote in a Washington Post article published Monday.

Other Republican senators who stand in firm opposition to Trump include Sens. Lindsey Graham (R-S.C.), Mark Kirk (R-Ill.), and Ben Sasse (R-Neb.).

Sen. Dean Heller (R-Nev.) has said he can’t envision himself voting for Trump at this time. “I’ll give him a chance, but at this point, I have no intentions of voting for him,” he said in June.

Another senator deeply critical of Trump is Sen. Jeff Flake (R-Ariz.), who warned the brash businessman could lose Arizona, which has been a GOP enclave for years. But the senator stopped short of saying he would not vote for him.

Like Flake, Sen. Ted Cruz (R-Texas) has not said explicitly that he would not vote for Trump. But in a speech at the GOP convention in Cleveland last month, Cruz urged delegates to vote their conscience “up and down the ticket,” signaling his opposition to the nominee.

Sen. Mike Lee (R-Utah), a friend of Cruz who hails from a state that has proven resistant to Trump, has also not offered his endorsement yet. While he has signaled his obvious displeasure ― earlier this year he said Trump scared him “to death” ― he could come around in the future if he “heard the right things out of him.”

At least three Republicans publicly supporting the GOP nominee have privately told The Huffington Post that they won’t vote for Trump in November.

Several other GOP members have yet to commit to endorsing Trump. House Energy and Commerce Chairman Fred Upton (R-Mich.) said he doesn’t expect to “endorse anyone in this race” and Rep. Mike Coffman (R-Colo.) is also reluctant to endorse Trump. He recently ran an ad in his district that is critical of both Democratic and Republican candidates. Rep. Bruce Poliquin (R-Maine) has refused speak publicly about the GOP nominee, even when asked for comment.

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims ― 1.6 billion members of an entire religion ― from entering the U.S.