Sen.(R-S.C.) on Friday said he would not vote for Donald Trump.

Graham is the highest GOP office holder so far to rule out voting for Trump.

Other Republicans, such as Sen. Ben Sasse (R-Neb.), have also said they won't support Trump in the fall, while Speaker(R-Wis.) said Thursday he couldn't yet support the controversial businessman.



“I also cannot in good conscience support Donald Trump because I do not believe he is a reliable Republican conservative nor has he displayed the judgment and temperament to serve as commander in chief," said Graham, who ran for president against Trump during the GOP primary.



Graham said after the November election he'd work with the next president to "deal with the many challenges facing our nation."



“I will enthusiastically support Republicans for other offices in South Carolina and throughout the country," he said, adding his focus was on supporting Republicans in the House and Senate.

Graham also announced he doesn't plan to attend the GOP convention in July in Cleveland. Several prominent Republicans, such as Mitt Romney and Jeb Bush, have said they don't intend to go, either.

The South Carolina senator said during a speech in Beverly Hills, Calif., this week that the GOP had "lost its way" with Trump, whose foreign policy views he harshly criticized. — This story was updated at 2:38 p.m.

“It’s hard to believe that in a nation of more than 300 million Americansand Donald Trump will be our choices for president," Graham said in a statement released by his Senate office.Graham said he'd "absolutely" not support Clinton, the overwhelming favorite for the Democratic nomination, saying she'd represent President Obama's "third term."