WASHINGTON — President Barack Obama will try to rev up Democrats in Ohio during a two-day visit, as the number of states that could swing to either Hillary Clinton or Donald Trump narrows to just a handful.

Obama heads to Columbus today to be the featured speaker at an annual dinner benefiting Ohio Democrats and Gov. Ted Strickland, who is running to oust incumbent Republican Sen. Rob Portman. On Friday, Obama will hold a rally in Cleveland for Clinton emphasizing early voting, a major focus for Democrats across the U.S. this year.

This week Obama entered the final 100 days of his presidency, and he’s increasingly devoting his time to trying to push Clinton over the finish line in the presidential race. With Trump and Republicans threatening to undo much of what Obama has accomplished over the last eight years, campaigning for Democrats is the most productive way for Obama to try to protect his legacy.

Before flying to Ohio, Obama planned to speak in Pittsburgh at the “White House Frontiers Conference,” where aides said he’d announce new funding for technology and research and tout innovations like self-driving cars and artificial intelligence. Obama, in an op-ed in the magazine Wired, said the U.S. needed to adapt its skills to address emerging threats like antibiotic-resistant “superbugs,” cybersecurity and climate change.

“To accelerate that change, we need science,” Obama said.

Ohio, with its diverse mix of cities and rural areas, is a coveted prize every four years, seen as a barometer for the shifts in the nation’s political climate. This year, it’s one of four states that polls suggest are currently tossups between Clinton and Trump, along with Nevada, North Carolina and Florida.

Trump, too, was setting his sights on Ohio today, with a speech in Columbus and an evening rally in Cincinnati.

The shrinking of the political battlefield reflects demographic shifts that have benefited Democrats in several states and Trump’s struggles to expand his appeal to a broad cross-section of America. But Obama and Democrats have been wary not to take anything for granted, particularly as the final weeks of the campaign have taken a series of unpredictable turns.