Obama hit on a common closing campaign theme of Democratic campaigns - defending the 2010 healthcare law that was his signature domestic achievement - while also urging Americans not to embrace hostility and division in politics.
That came as Trump has hammered relentlessly on his hard-line immigration theme in his frequent rallies supporting Republican candidates in Tuesday's elections, painting a grim and sometimes misleading impression of his rivals' political goals.
"In the closing weeks of this election, we have seen repeated attempts to divide us with rhetoric designed to make us angry and make us fearful," Obama said at a rally in Miami. "But in four days, Florida, you can be a check on that kind of behavior."
Obama appeared in Miami with gubernatorial candidate Andrew Gillum, who faces former congressman Ron DeSantis, a strong Trump backer, and U.S. Senator Bill Nelson, who is being challenged by the outgoing governor, Rick Scott.
A Reuters/Ipsos/UVA Center for Politics poll this week showed both Democrats leading with voter enthusiasm for Gillum, the young and liberal Tallahassee mayor, appearing to help Nelson and other Democratic candidates on the ballot.
Trump was to appear at rallies on Friday on behalf of Republicans who are challenging incumbent Democratic U.S. senators in West Virginia and Indiana, states he won in the 2016 presidential election.
Opinion polls and non-partisan forecasters generally show Democrats as having strong chances of winning 23 additional seats and taking a majority in the U.S. House of Representatives, which they could use to launch investigations into Trump's administration and block his legislative agenda.
Republicans are generally expected to retain control of the U.S. Senate, whose powers include confirming Trump's nominations to lifetime seats on the Supreme Court.
Obama's speech was repeatedly interrupted by hecklers, prompting him to quip, "Why is it that the folks who won the last election are so mad all the time?"
SURGING EARLY VOTING
Interest in the vote has been unusually high for a year when Congress but not the White House is at stake, according to early voting tallies. Twenty-seven states plus the District of Columbia have recorded more early votes at this point in the campaign than they did in all of 2014, according to The Election Project at the University of Florida, which tracks early turnout.
Texas had already recorded more votes than it did in all of 2014, including Election Day, the group said.
After Miami, Obama will head to Georgia to campaign for Stacey Abrams, a former state legislator aiming to become the United State's first black female governor.
Obama's challenge will be motivating the diverse coalition of voters who elected him in 2008 and 2012 but failed to turn out in as large numbers in 2016, said Patrick Hickey, a professor of political science at West Virginia University.
"Hillary Clinton lost because the Obama coalition didn't show up at the polls – he's trying to mobilize folks who like him and trust him in Georgia and Florida," Hickey said.
In West Virginia, Trump will campaign for a third time with Patrick Morrisey, who aims to unseat Democratic Senator Joe Manchin.
Two new polls this week showed Manchin's once-comfortable lead over Morrisey dwindling to 5 percentage points, which the Democrat's supporters blame in part on Trump's repeated visits.
"I know Trump coming so often is making an impact," said Jim Hoyt, chairman of the Morgan County Democratic Party in northeast West Virginia. Like other Democrats in the state, he still expects Manchin to win.
Trump also will go to Indiana to appear on behalf of Mike Braun, who is trying to replace Joe Donnelly in the Senate.
For all Reuters election coverage, click: https://www.reuters.com/politics/election2018
(Reporting by Joe Skipper in Miami and Sharon Bernstein in Sacramento, California, additional reporting by Amy Tennery in New York Writing by Scott Malone Editing by Bill Trott)
(This story has not been edited by Devdiscourse staff and is auto-generated from a syndicated feed.)