CLEVELAND — This spring Ohio Democratic Party Chairman David Pepper went to White House officials with a single request: have President Obama visit the state in the final weeks of the 2016 campaign.

On Thursday Obama delivered, unleashing a full-throated attack on Ohio Republicans in Columbus as part of the first stop in a two-day swing through the state. Detailing a litany of conspiracy theories that have dogged his presidency, he said, “So the point is, if your only agenda is either negative — negative is a euphemism, crazy — based on lies, based on hoaxes, this is the nominee you get.  You make him possible.”

“So don't act like this started with Donald Trump. He did take it to a whole new level. I got to give him credit,” he said, speaking at Ohio Democrats’ annual dinner. “But he didn’t come out of nowhere. And that's why we've got to win this election at every level.”

The question now facing his party is whether the president can energize enough of his supporters to overcome Donald Trump’s appeal in one of the Rust Belt states the businessman is best positioned to win this year. While Trump’s lead over Democratic nominee Hillary Clinton has shrunk in recent days, it remains a tossup: a new NBC-Wall Street Journal-Marist poll released Thursday gave Trump a 1-point edge.

“The way we win Ohio, we have to reconstitute the Obama coalition,” Pepper said in an interview Thursday, adding that the president’s “personal presence makes an enormous difference.”

Obama’s two stops here — first at the state party dinner, and then a rally Friday morning in Cleveland — are aimed at boosting turnout among millennials and African Americans in urban areas. Those groups were critical to the president winning Ohio in both 2008 and 2012

But as Trump has made inroads among the white, working-class segment of the state's electorate, the role of young voters, African Americans and women have become even more pivotal this year.

Nationally, Clinton remains much less popular with millennials compared to Obama, and trails him by a smaller margin when it comes to black voters. Sixty-six percent of registered voters under 30 surveyed in a late-September Washington Post-ABC poll said they approve of the president, compared to just 35 percent who declared the same of Clinton. Among African Americans, Obama won a 91 percent approval rating compared to Clinton’s 83 percent.

On the campus of Case-Western University, the challenge Clinton faces among young voters is clear. Three seniors, sitting at a table at the university’s student center, said they were unenthusiastic about backing the Democratic nominee despite their distaste for Trump.

Gabriel Murcia, a 21-year senior, volunteered for Obama’s reelection campaign as a high-school student in Lancaster, Penn.

“I was on the Obama train, back in the day,” he said, adding that while Trump “is pretty awful,” it sometimes prevents people from looking “critically at the way [Clinton’s] policies have negatively affected people of color both here and abroad, working people and LGBTQ people.”

Murcia plans on voting next month, at least so he can weigh in on local races. “But in terms of the presidential election, whether I can find it in my conscience to vote for Hillary, I don’t know.”

Libertarian party candidate Gary Johnson has gained some traction in Ohio — he garnered 9 percent of the vote in Thursday's NBC-WSJ-Marist poll — while Green party candidate Jill Stein has been siphoning off a smaller share of the state's electorate as well.

Eliana Ondrejko, a 19-year old sophomore, said she and most of her friends back Clinton, and have been reminding others of what it means to opt for a third party. “We definitely look at third parties as a distraction from Hillary,” she said. “It’s voting for Trump.”

“That’s what my suitemates keep saying,” chimed in Lauren Spizman. “Direct quote.”

The White House is arranging a series of media appearances for the president to reach these targeted groups, whether it is through local radio interviews, national television interviews or digital outreach. On Thursday, before leaving Pittsburgh for Columbus, he taped a skit with Stephen Colbert that will air on The Late Show on Monday

"President Obama has long engaged with a wide array of outlets to meet people where they are, advance his policy agenda, and communicate about issues that matter most to the American people — from talking climate change with Bear Grylls, to slow jamming the news about trade with Jimmy Fallon,” White House spokeswoman Jennifer Friedman said in an email, adding he planned to do more of these appearances “in the coming weeks.”

Ohio Democrats, for their part, say that while they still have work to do to mobilize segments of the coalition that helped elect Obama and keep him there, they are confident they have developed the infrastructure on the ground to accomplish that.

“Whether someone likes someone or loves someone, as long as they’re gotten to the polls, a vote is a vote is vote,” said P.G. Sittenfeld, a Cincinnati city council member who ran against former Ohio Gov. Ted Strickland in the state’s Democratic Senate primary this year.

Clinton’s Ohio director Chris Wyant, who directed the state Democratic Party’s effort on behalf of Obama’s 2012 reelection and deputy field director for Obama here in 2008, said the campaign has applied “the lessons learned” during the past two presidential races to develop a more robust ground game. As early voting began on Wednesday, he noted, the campaign had events in each one of the state’s 88 counties.

“Even in 2012, I don’t think we had events and supporters in every county out on the first day,” Wyant said. "Across the state, we saw really encouraging numbers."

Trump has a less robust field operation than Clinton but has drawn much larger crowds than her during his repeated visits here, including one to Cincinnati on Thursday.

"Hillary Clinton has had her hands on all of the bad trade deals over the last 23 years that have sent Ohio jobs overseas, and has a hard time hiding her disdain for regular working Americans.," said Trump's Ohio communications director Seth Unger in an email. "Mr. Trump's America First message is resonating across Ohio, particularly among disaffected Democrats and independents in regions of the state like the Mahoning Valley and Appalachia where traditional Republicans have struggled."

"Hillary wants to end forever the American independence," he told the crowd of more than 21,000 at the city's U.S. Bank Arena. "Either we win this election, or we lose our country."

Sen. Rob Portman (R-Ohio), who is up for reelection this year and holds a comfortable lead over Strickland, has spent nearly two years developing an extensive grassroots operation in the state. According to his campaign manager Corry Bliss, by the end of this week the campaign will have personally contacted 4.5 million of the state’s roughly 7.8 million registered voters.

The campaign has identified “22 distinct and separate buckets of targeted voters,” Bliss said, including 80,000 living near Lake Erie who consider addressing harmful algae blooms as one of their top priorities. Portman’s campaign has also drawn support from less traditional places. It recruited 500 college and high-school students to work as summer interns, has won the endorsement of four major unions, including the Teamsters, and nearly three dozen African American pastors.

With voting underway, it is too early to tell if the Clinton campaign’s grassroots organizing can give her the boost she needs in key Democratic strongholds. Absentee ballot requests are down 17 percent in Cuyahoga County, which includes Cleveland, and whose 236,000-vote advantage for Obama in 2012 was more than enough to deliver the state to Democrats last time.

“You got to start making those calls and knocking on doors, getting everybody out to vote early,” Obama told Ohio Democrats Thursday. “That’s how we won in 2008. That’s how we’re going to win in 2016.”

That sort of message, Wyant said, is critical, “Conveying to those supporters that, frankly, voting isn’t enough. It’s really time to get engaged.”

Emily Guskin contributed to this report.