Mook said the campaign is also planning to spend an additional $2 million in Arizona on television and digital advertising as well as mail pieces. The campaign had a limited TV buy in the state last month.
The campaign will also make a new, one-week ad buy in Texas, a state no Democratic presidential nominee has won since 1976, according to a Clinton aide. The ad highlights the Dallas Morning News's endorsement of Clinton, the first time the paper has backed a Democrat for president in a century. It will air in Dallas, Houston, Austin, San Antonio and online.
The new activity comes as the Clinton campaign weighs how aggressively to expand its efforts beyond core battleground states in the final weeks of the campaign, as Trump has faltered amid accusations about his treatment of women and started complaining about a “rigged” election.
“Donald Trump’s campaign is spiraling,” Mook said on a conference call with reporters. “He knows he’s losing, and he’s trying to blame it on the system. That’s what losers do.”
Mook said Clinton’s campaign remains committed to the seven battleground states where it is currently airing television ads, and he said it plans “enhancements” in those places partly to help other Democratic candidates on the ballot.
But Mook said the campaign is continuing to look at other opportunities, including Utah, another traditionally Republican state where the race has tightened. No Democrat has carried Utah in a presidential race since 1964.
The first lady’s planned visit to Phoenix on Thursday will be the third visit to Arizona by a high-profile surrogate in as many days. The campaign is deploying Sen. Bernie Sanders of Vermont on Tuesday and the nominee's daughter, Chelsea Clinton, to the state Wednesday.
The last Democrat to carry Arizona in a presidential race was Bill Clinton in 1996.
Mook also announced Monday that the Hillary Victory Fund would invest $1 million in Indiana and Missouri, two states where he acknowledged that Clinton faces an uphill battle. But Mook said the money should help with other competitive races in those states.
The Hillary Victory Fund is a joint effort by the Clinton campaign and the national and state Democratic parties.
Mook said the coordinated campaign has now invested more than $100 million in battleground states.
Anne Gearan contributed to this report.