Priorities USA Chairman Guy Cecil said the group is primarily targeting voters in Pennsylvania, Michigan, Wisconsin, New Hampshire, Nevada and Florida. The online ads will focus on Trump's handling of the economy.
Cecil said the economy may be doing well overall under Trump, but polling shows many Americans feel the prosperity hasn't trickled down.
He said wages haven't kept pace, health care and college remain unaffordable and the tax cut championed by Trump and the GOP primarily rewarded the wealthy.
"Most Americans describe the economy as being good. Most Americans also describe their own situation as being tenuous," Cecil said. "Our job is to make sure we are constantly putting these types of things in context."
The challenge will be breaking through the noise coming from the White House and Washington to get voters in crucial battlegrounds to focus on economic issues, he said.
It's unclear how much Priorities will spend overall. During the 2016 election, the group raised about $200 million.
Surveys conducted by the group suggest Trump is vulnerable in many of the same Rust Belt states that sealed his victory in 2016, such as Michigan, Wisconsin and Pennsylvania, as well as Florida.
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