A Republican lawmaker in Congress became the first to break with his party over the White House campaign on Tuesday, denouncing presidential candidate Donald Trump as unfit to lead and pledging to vote for Democratic rival Hillary Clinton.

The break followed days of dispute between Trump and the parents of a Muslim US Army officer killed in the Iraq war that has fueled fresh unease among many Republicans over the New York businessman's policies and style.
In an op-ed piece, Representative Richard Hanna of New York cited Trump's attacks on the parents, calling the candidate "deeply flawed in endless ways," "unrepentant" and "self-involved."
"For me, it is not enough to simply denounce his comments: He is unfit to serve our party and cannot lead this country," Hanna wrote in the letter posted on syracuse.com, the website of the Post-Standard newspaper in New York.
While some lawmakers have not actively endorsed Trump, Hanna was the first to say he would vote for Clinton in the Nov. 8 election.
Trump has criticized Khizr Khan and Ghazala Khan since they took the stage at last week's Democratic convention. Khizr Khan cited their son Humayun Khan's military service and sacrifice and criticized Trump's proposed temporary ban on Muslims from entering the United States.
Many Republicans have expressed support for the parents in recent days, and some have sharply rebuked Trump, most notably Senate Armed Forces Committee Chairman John McCain, a military veteran and former prisoner of war.
Hanna is retiring from the House and is not seeking re-election, leaving him more leeway to risk upsetting colleagues and voters over his break with Trump.
"While I disagree with her on many issues, I will vote for Mrs. Clinton. I will be hopeful and resolute in my belief that being a good American who loves his country is far more important than parties or winning and losing. I trust she can lead," Hanna wrote.
In the fallout over Trump's dispute with the Khans, Republican Senate Majority Leader McConnell and House Speaker Paul Ryan have also supported the family. Still, top Republican lawmakers have not withdrawn their support for Trump as the party's presidential pick.
Ryan's office declined to comment on Hanna's announcement.

'Incendiary comments'

Trump's presidential campaign has appealed to Capitol Hill for support amid the controversy, including circulating talking points for lawmakers to use, but has found little support.
Trump's son, Eric Trump, told CBS News on Tuesday that his father's comments toward the Khans have been "blown hugely out of proportion."
US Republican Representative Charlie Dent, who has not endorsed Trump, criticized the candidate's tone on Tuesday and called for more measured responses, telling MSNBC his "incendiary comments ... are causing real problems."
Dent added that he was not shocked by Hanna's break with the party, although he said he himself has no plans to support Clinton.
"Like me, I think he's also been very concerned about the incendiary statements plus the lack of solid policy," coming from Trump, said Dent of his House colleague.
Trump, a former reality TV star, has never held political office but beat 16 rivals to win the party's primary contests and become the party's White House nominee.
He has troubled many in the Republican establishment with his off-the-cuff, often insulting style, and controversial policies including the proposed ban on Muslims and his plan to build a wall along the Mexican border to keep out illegal immigrants.