An overwhelming majority of voters are disgusted by the state of American politics, and many harbor doubts that either major-party nominee can unite the country after a historically ugly presidential campaign, according to the final pre-election New York Times/CBS News Poll.

In a grim preview of the discontent that may cloud at least the outset of the next president’s term, Hillary Clinton and Donald J. Trump are seen by a majority of voters as unlikely to bring the country back together after this bitter election season.

With more than eight in 10 voters saying the campaign has left them repulsed rather than excited, the rising toxicity threatens the ultimate victor. Mrs. Clinton, the Democratic candidate, and Mr. Trump, the Republican nominee, are seen as dishonest and viewed unfavorably by a majority of voters.

While her advantage has narrowed since mid-October, Mrs. Clinton still has an edge in the survey because of a commanding advantage among women and nonwhite voters. She has the support of 45 percent of likely voters while Mr. Trump has 42 percent. Gary Johnson, the Libertarian nominee, has slipped to 5 percent, and Jill Stein, the Green Party candidate, is at 4 percent.

If she wins, Mrs. Clinton will enter the White House to face immediate governing challenges not only from the deep partisanship ruling Washington but also from a large number of Mr. Trump’s supporters who say they are not prepared to accept the results.

Republican anger is directed not only at Mrs. Clinton or the electoral process. About as many Republican voters say Mr. Trump’s candidacy has been bad for the party as believe his campaign has been positive for Republicans, an extraordinary divide over their own standard-bearer on the eve of the election.

As Republicans face the possibility of their third consecutive presidential loss, their own voters overwhelmingly acknowledge the party is facing a schism: 85 percent of Republican voters said the party was divided, and only 14 percent said it was united.

But Republicans cannot even agree on who is to blame for the division, though they largely believe Mr. Trump has been the impetus for the breach, according to some follow-up interviews.

“I think Donald Trump has definitely divided the party,” said Sheila Wagner, 79, a Republican from Redmond, Wash. She said she had already marked her ballot for Mrs. Clinton, adding: “When he first declared he was going to run, I thought it was a joke. I just couldn’t believe anyone would favor him.”

Yet other Republicans point the finger at Republicans who have refused to support Mr. Trump.

“The old school, quote unquote, the Bushes, the people who have been around a long time, aren’t supporting Trump, and that’s creating division,” said Nora Reinhardt, 66, a farmer from Holt, Mo. “Some Republicans, because of comments Trump has made, which I grant are uncouth and certainly not politically correct, have found they can’t support him, although I think some of those people are coming around at this point.”

She said she was supporting Mr. Trump because she agreed with his policy positions.

Whatever their reasons, and despite how many of them think Mr. Trump has been detrimental to the party, more than eight in 10 Republican voters are falling in line behind their nominee.