Hillary Clinton has surged to a 15-point lead over reeling, gaffe-plagued Donald Trump, according to a new McClatchy-Marist poll.

Clinton made strong gains with two constituencies crucial to a Republican victory – whites and men — while scoring important gains among fellow Democrats, the poll found.

Clinton not only went up, but Trump went down. Clinton now has a 48-33 lead, a huge turnaround from her narrow 42-39 advantage last momth.

The findings are particularly significant because the poll was taken after both political conventions ended, and as Trump engaged in a war of words with the parents of Army Capt. Humayun Khan, killed in the Iraq War 12 years ago.

“This is coming off the Democratic convention, where a bounce is expected,” said Lee Miringoff, director of the Marist Institute for Public Opinion in New York, which conducted the nationwide survey.

“What you don’t want is to have the worst week of your campaign” – a characterization many analysts use to describe Trump’s recent days.

Other polls have shown Clinton in the lead, though Marist’s is the largest so far.

Among poll respondents, Clinton was seen more often as a potential president. Fifty-three percent said they would find her acceptable; 39 percent felt that way about Trump.

In a four way race, Clinton retains her lead. She gets 45 percent to Trump’s 31 percent. Libertarian Gary Johnson has 10 percent and the Green Party’s Jill Stein has 6 percent.

The new survey showed Clinton has cut sharply into the Republican nominee’s advantages in every ethnic and racial group.

After a bitter battle with rival Bernie Sanders, the independent Vermont senator whose supporters fought all the way to the convention, she’s solidified her strength among Democrats, 90 percent of whom now back her, up from 83 percent last month.

Trump gets the nod from just 79 percent of Republicans, down from 85 percent last month. Some top GOP officials have put distance between themselves and the billionaire businessman, with some saying they’ll back Clinton.

Men had been the bedrock of Trump support. Last month, he was up by 14 percentage points among men; he’s now down 8. Clinton remains strong with women, as she’s up 20.

Trump collapsed almost everywhere that he’d built decent support. Even among white voters, which favored Republican White House candidates in recent elections, Trump was lagging, ahead of Clinton, but only just barely, 41-39.

That’s a troubling finding for a Republican. 2012 Republican nominee Mitt Romney won whites by 20 points, and still lost the election. In 2008, Sen. John McCain, R-Ariz., won the white vote by 12 points and lost.

Clinton wins moderates, 50-27 percent. She is far ahead with black voters, 93-2 percent, and with Latinos, 55-26 percent.

More encouraging to Clinton, 57 percent of her backers say their vote is for her, while 40 percent say it’s largely an anti-Trump vote.

Most of Trump’s backers – 57 percent – say their vote is against Clinton, while 36 percent called it a pro-Trump decision.

On issue after issue, Clinton ranked ahead of Trump. She’s up by 8 when asked who can best handle the war on terror. She’s ahead 21 on immigration, 14 on gun violence, 14 on trade and 4 on creating jobs, which had been one of Trump’s strengths.