Donald Trump warns voters of Clinton 'problems'

Donald Trump has warned that a cloud of investigation would follow Hillary Clinton into the White House, evoking the impeachment battle of the 1990s in a closing campaign argument meant to bring wayward Republicans home.

Mrs Clinton and her allies, led by President Barack Obama, told voters to get serious about the alternative.

Negative exchanges between the Republican businessman and his Democratic rival signalled the campaign was likely to end on a low note as polls show Mr Trump closing in on Mrs Clinton in key battleground states.

Her shrinking lead has given Mr Trump's campaign a glimmer of hope, one he is trying to broaden into breakthrough before time runs out.

That means courting the moderate Republicans and independents who have been the holdouts of his campaign, voters turned off by Mr Trump's controversies but equally repelled by the possible return of the Clintons.

Mr Trump directed his message at those voters at a rally in Jacksonville, Florida, where he zeroed in on questions of Mrs Clinton's trustworthiness and a new FBI review of an aide's emails.

"Here we go again with the Clintons - you remember the impeachment and the problems," Mr Trump said. "That's not what we need in our country, folks. We need someone who is ready to go to work."

Mr Obama and allies, meanwhile, are seeking to keep the spotlight on Mr Trump, charging that his disparaging comments about women and minorities make him unfit for office.

The stakes are higher than a typical election and Americans need to get serious about the choice, Mr Obama told students at Florida International University in Miami.

"This isn't a joke. This isn't 'Survivor.' This isn't 'The Bachelorette.'" Mr Obama said. "This counts."

Mr Obama openly taunted the former reality-TV star, zig-zagging from mockery to dire warnings to boasting about his own record in office.

The president's mission in the final push before Tuesday is to fire up the Democratic base - and bait the Republican into veering off message.

The famously unconventional Mr Trump has so far hewed closer to convention, running some upbeat ads, bringing out his wife for a rare campaign appearance and even talking publicly about trying not to get distracted.

"We don't want to blow it on November 8," Mr Trump said on Thursday.

Mr Trump must win Florida to win the White House.

His campaign has been buoyed by tightening polls in the state and other key battlegrounds, as well as by signs that African-American turnout for Mrs Clinton may be lagging.

Mrs Clinton's team will try to drive up enthusiasm in the final weekend, capping its efforts by bringing Mrs Clinton and Mr Obama together, along with their spouses, for a final pre-election rally in Philadelphia on Monday evening.

Mr Trump's wife Melania was to campaign in a suburb of Philadelphia on Thursday, her first turn on the trail since the Republican convention in July.

The former model is trying to counter the Clinton campaign's pounding attacks on her husband as anti-woman.

Mr Trump is not the first Republican to raise warnings of a new cycle of scandal and investigation.

Republican lawmakers have recently threatened to block Mrs Clinton's Supreme Court nominees, investigate her endlessly or even impeach her over her use of private emails as secretary of state.

House Democratic leader Nancy Pelosi said any effort to impeach Mrs Clinton "would be a brazen attempt to nullify the vote of the American people" and would be a waste of time and taxpayers' money.