WASHINGTON -- Hillary Clinton is seizing opportunities presented by a volatile presidential race to expand her base of support heading into the fall, seeking to position the Democratic Party for a sweeping victory in November.

As Donald Trump struggles through a second week of self-inflicted blunders, the Democratic nominee's campaign has started to push into Republican territory by courting some of the party's core supporters and expanding her campaign's operations into traditionally Republican states.

"The map favours us and, in a way, the dynamics right now favour us," said Joel Benenson, Clinton's senior strategist. "The more places you can make them play defence, the better off we are."

Throughout his presidential bid, Trump has used controversy to draw attention back to his campaign. It's a strategy that initially worried some Clinton aides, who feared he would drown out their candidate's general-election message.

But with three months until Election Day, Clinton aides say they see more advantages than liabilities as Trump continues to venture into the politically unimaginable. Critics slammed Trump this week for appearing to suggest that gun-rights supporters could shoot Clinton to prevent her from appointing federal judges as president, and he drew criticism for standing by a false claim that President Barack Obama founded the Islamic State.

Clinton, too, faced her own bad headlines this week, with the release of a new batch of State Department emails that renewed questions about whether Clinton used her government post to benefit the Clinton foundation.

Democratic strategists have long argued the party could win the White House with Obama's political coalition, the group of minority, young and female voters who twice boosted him to victory. They see the additional support Clinton is finding among independent and Republican voters as the frosting on their electoral cake.

"You care very deeply about the 270th electoral vote, but there are also important reasons to care about winning big," said Geoff Garin, a pollster for Clinton's 2008 presidential campaign who now advises the pro-Clinton super PAC Priorities USA Action.

Clinton aides say she's taking nothing for granted, noting the U.S. remains a politically divided country. Yet Clinton is undoubtedly beginning to cast her gaze beyond the Democratic base.

"I am humbled and moved by the Republicans who are willing to stand up and say that Donald Trump doesn't represent their values," she said at a rally in Iowa this week. "We may not agree on everything, but this is not a normal election and I will work hard over the next three months to earn the support of anyone willing to put our country first."

On Wednesday, following two weeks of high-profile Republican defections, her campaign launched an official effort to target GOP voters, telling party officials in Arizona and Georgia they plan to make a six-figure investment in field operations in both states.

The next day, Clinton published a column in Salt Lake City's Deseret News titled "What I have in common with Utah leaders -- religious freedom and the Constitution." While the state has not backed a Democrat for president since Lyndon Johnson in 1964, Trump himself acknowledged Thursday he is "having a tremendous problem in Utah."

And on Friday, she attempted to undercut Trump's business record by releasing her 2015 tax returns. Trump has broken with decades of presidential candidates by refusing to make his filings public. He says they're under audit by the Internal Revenue Service and that he'll release them only once that review is complete.

While the millions of dollars Clinton has earned offers fresh fodder for Republican critics, her campaign believes those attacks are outweighed by the opportunity to raise questions about Trump's honesty.

Democrats believe Trump's returns could be treasure trove of politically damaging information, including his low tax rate, minimal charitable giving, and business dealings with foreign governments.

Jeremy Bird, who ran field operations for Obama's 2012 campaign and is now consulting for Clinton's operation, said Trump has no one to blame but himself. The unorthodox candidate hasn't aired a single television ad since the end of the primaries and is building a bare-bones effort to get out the vote.

"His inability to put anything real on the ground in battleground states is campaign malpractice," Bird said. "There are just so many paths to 270 and so many ways to put their presidential campaign and the Republican Party in a defensive posture, even in states that are not considered battlegrounds."

Some recent polls suggest Clinton could also benefit from Republican-leaning voters deciding to stay home rather than come out to support Trump. Surveys in Wisconsin, Pennsylvania and Ohio found that 90 per cent of Democrats said they intended to support Clinton, while closer to 80 per cent of Republicans intended to support Trump.

Republicans caution the race remains far from settled, especially since voters don't particularly like either candidate. A small group of middle-class mothers interviewed by pollsters Tuesday in Columbus, Ohio, and Phoenix used words such as "painful," "nauseated" and "screwed" to describe their choice.

"They don't trust Hillary Clinton," said Republican pollster Neil Newhouse, part of the bipartisan team that conducted the focus groups. "At the same time, they can't turn to Donald Trump because he scares them."

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AP Polling Editor Emily Swanson contributed to this report.