WASHINGTON -- Donald Trump's campaign is planning its biggest ad buy to date, upward of $10 million on commercials airing over the next week or so.

The campaign said ads will begin airing Monday in nine states: Ohio, Pennsylvania, North Carolina and Florida, where the campaign has already been on the air, along with New Hampshire, Virginia, Iowa, Colorado and Nevada. They're all important swing states.

Trump has so far been badly outspent by his Democratic rival, Hillary Clinton, and groups supporting her candidacy.

The new investment comes amid signs that Trump's lagging poll numbers may be improving against Clinton's following a campaign reboot.

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