Hillary Clinton is pushing her supporters to cast early ballots in key battleground states in the race for the White House, as Donald Trump tries to make up ground with intensified attacks following the FBI's renewed examination of her email practices.
As her national lead shrinks in the final week of the race, Democratic candidate Mrs Clinton is relying on a firewall of support in more demographically diverse swing states.
With more than 23 million ballots already cast through early voting, it is unclear whether Republican candidate Mr Trump has the time or organisational capacity to improve his standing enough over the next week to win the US election.
While Mrs Clinton's newest email controversy may help Mr Trump pick up support in older, whiter states such as Ohio and Iowa, the Republican nominee still faces a narrow pathway to winning the required 270 electoral votes - one that includes defending states such as Arizona and Utah which Republicans have won for decades.
Both campaigns argued they were on the path to victory in interviews with ABC's Good Morning America.
"We're running like we're 20 points behind," said Clinton campaign manager Robby Mook.
"We are going to win this election, but it's important that every one of our supporters turns out."
Meanwhile, Trump campaign chief David Bossie said: "We're in great shape. We're on offence everywhere.
"There's an enthusiasm gap for their voters."
With just a week to go before US election day, the race for the White House remains a test of one question: Will the conventional rules of modern-day campaigns apply to a 2016 election which has been anything but conventional?
Mrs Clinton's campaign has spent nearly two years developing an extensive apparatus, building off the political machine which twice boosted Barack Obama to victory.
Her team has pounded the airwaves with advertising, assembled an expansive voter data file and constructed a nationwide political organisation which dwarfs her opponent's.
Mrs Clinton's team is focused on pushing voters to the polls for early voting in critical states such as Florida, Nevada and Colorado, where one third of the expected ballots have already been cast.
On Tuesday, she plans to pound Mr Trump at rallies across Florida.
The Democratic presidential nominee and her allies in a dozen battleground states have more than 4,800 people knocking on doors, making phone calls and otherwise working to support her candidacy. Mrs Clinton's numbers, as reported in recent campaign filings, tripled those of Mr Trump and the national and state Republican parties.
The New York businessman over the past year has largely ignored the key components of recent winning campaigns, depending instead on massive rallies and free media coverage to drive his outsider candidacy.
This week, he is devoting his time to states where polls suggest he is trailing his Democratic opponent by significant margins.
Mr Trump took part in two rallies in Michigan, a state which last backed a Republican presidential nominee in 1988. On Tuesday, he is scheduled to appear with running mate Mike Pence in Wisconsin, which has not backed a Republican for president since Ronald Reagan's re-election in 1984.
Pointing to renewed FBI examination of Mrs Clinton's email practises as evidence she could face a criminal trial as president, Mr Trump said: "Her election would mire our government and our country in a constitutional crisis that we cannot afford."
Mrs Clinton, defending herself from the new FBI examination, focused on Ohio, a state which Mr Trump's team concedes he must win and where he shows signs of a possible victory.
"There is no case here," she insisted. "Most people have decided a long time ago what they think about all this."
Clinton campaign manager Robby Mook later decried what he called a "blatant double standard" following a CNBC report that FBI director James Comey opposed releasing details about possible Russian interference in the US election because it was too close to election day.
Mr Comey issued a letter to congressional leaders on Friday about the FBI's renewed interest in Mrs Clinton's email.
Meanwhile, the ongoing mystery of Mr Trump's tax returns arose again. The New York Times reported that in the 1990s, the billionaire avoided paying potentially hundreds of millions of dollars in taxes in a way even his own lawyers considered questionable, using a manoeuvre US congress explicitly banned in 2004.
A spokeswoman said Mr Trump's approach was appropriate.
As for Mr Trump's charge that a Clinton election win might prompt "a constitutional crisis", the US justice department's office of legal counsel said in 1973 that criminally prosecuting a president would unconstitutionally undermine the executive branch.
A 2000 memo reached a similar conclusion, although American presidents can face civil lawsuits.