Republican presidential candidate Donald Trump’s support has surged and he is now running nearly even with Democratic candidate Hillary Clinton among likely U.S. voters, a new Reuters poll released Wednesday found.

The new poll marks a dramatic turnaround for Trump since he became the Republican party’s presumptive presidential nominee last week.

The results could signal a close fight between the two likely White House rivals as Americans make up their minds ahead of the November 8 election to succeed Democratic President Barack Obama. As recently as last week, Clinton led Trump by around 13 points in the poll, noted Reuters.

But in the latest survey, 41 percent of likely voters supported Clinton, the Democratic front-runner, and 40 percent backed Trump, with 19 percent not decided on either yet, according to the online poll of 1,289 people conducted from Friday to Tuesday.

The poll had a credibility interval of about 3 percentage points.

The results reflect a big increase in support for Trump since he knocked out both Senator Ted Cruz of Texas and Ohio Governor John Kasich last week to become the last Republican in the White House race.

Clinton, who has all but clinched the Democratic nomination over rival Bernie Sanders, has mostly led Trump in the head-to-head poll this year. Trump briefly matched her support a few times in 2016, most recently in mid-March, after Senator Marco Rubio of Florida, a favorite of the Republican establishment, dropped out.

The poll follows a Quinnipiac University poll released on Tuesday and which found that Clinton and Trump are neck and neck in the key states of Pennsylvania, Ohio and Florida.

Opinions are likely to change over the next six months as American voters become inundated with hundreds of millions of dollars in campaign advertising, highly publicized debates and a pair of party conventions.