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Clinton campaign spends big with more ads in Iowa, New Hampshire

Democratic presidential candidate Hillary Clinton speaks about college affordability during a town hall meeting in Dubuque, Iowa, Aug. 14, 2015.

Reuters/Joshua Lott

As some polls show Hillary Clinton's lead slipping in early-voting state polls, her campaign is ramping up its advertising in Iowa and New Hampshire, extending its initial television ad buys until the end of October.

Clinton's first television ads appeared in early August, running as 60-second spots in Iowa and New Hampshire, and they were set to continue for five weeks. But a Clinton aide told CBS News that the presidential campaign wants to continue running those same ads, reserving more television time through September and October.

The ad buy will cost the campaign a total of $4.1 million, a Clinton aide confirmed to CBS News. About $1.5 million will be spent in Iowa, focusing on the Des Moines and Cedar Rapids markets. The campaign will also reserve air time in Manchester, Boston and Burlington, Vermont, spending a total $2.6 million for ads covering New Hampshire.

This ad spending links the initial five-week buy with a previously announced November ad buy so the campaign "will not go dark" in between.

Hillary Clinton's campaign has faced mounting competition in recent weeks, with Vermont Sen. Bernie Sanders closing in on the front-runner's lead in Iowa and Vice President Joe Biden emerging as another possible contender for the Democratic nomination. Clinton's campaign is also fighting back against increasing scrutiny over her private email use while at the State Department.

CBS News Digital Journalist Hannah Fraser-Chanpong contributed to this report.