Pro-Trump super PAC America First Action is preparing to unleash a series of targeted, swing-state attacks on the Democrat most likely to face President Trump after Super Tuesday, people familiar with the group's plans tell me in an exclusive preview of its strategy.

The state of play: The group has been tracking favorable/unfavorable ratings in Florida, Georgia, Michigan, North Carolina, Ohio and Pennsylvania for 2020 candidates Joe Biden, Bernie Sanders, Elizabeth Warren, Pete Buttigieg and Michael Bloomberg — under the theory that if Trump wins each of these six states he would win re-election.

The spending isn't expected to begin until it’s clear who the Democratic nominee will be, whether that's after next week's Super Tuesday or in July at the Democratic National Convention.

It sees Sanders or Bloomberg as the most likely nominees — as of now.

The attacks will be targeted to specific audiences in each state, based on rich data gathered beginning last August. The super PAC has pulled together about 500 pages of research on four of the five candidates, with about 300 pages on Buttigieg, given his shorter record.

Their onslaught will come in the form of high-dollar digital and TV ad buys and mailers, one of the people familiar with the strategy said.

Details: Axios reviewed overall and state-by-state data the group provided on each of the candidates. (The group did not poll Trump favorability numbers as part of this effort, the person said.)

Biden still enjoyed the most favorable numbers of those Democrats in each of the six states, but slid underwater between last August and this January, from 46%-48%- favorable/unfavorable to a 44%-50%.

By January, Sanders' favorability was highest in Michigan (44%) and lowest in Ohio (38%). His unfavorable numbers in Florida (54%) led America First officials to believe that could take that key state off the table if Sanders becomes the nominee, and allow them to shift their resources to Michigan and other places where his message seemed to resonate with blue-collar, union workers.

Bloomberg's six-state average was 34%-45% favorable/unfavorable. The strategists said they expect him to struggle more in culturally conservative states with strong pro-gun cultures, and perform stronger in states like Pennsylvania that have "the northwestern mentality."

Warren's average slid between August and January, from 39%-45% favorable/unfavorable to 38%-51%.

Buttigieg, who only polled by the group in January during its second wave of surveys, had an average of 32%-36% favorable/unfavorable across the six states.

Methodology: The super PAC conducted live-caller surveys of likely voters in the six states in August 2019 and the second half of January 2020, with sample sizes ranging from 800-1,000 per survey. The likely voters were on average slightly more Democrat, 40.2% to 37.5%. The margins of error in these surveys ranged from 3.1%-3.5%, according to the group.