A dozen congressional Democrats are considered possible candidates.
The ads are critical of Democratic Senators Tammy Baldwin of Wisconsin and Claire McCaskill of Missouri.
“Every nation that’s prospered is one that didn’t engage in trade wars,” he said.
The network, with more than 700 donors who give at least $100,000 per year, will outlive the brothers, members say.
Blackstone CEO Stephen Schwarzman gave $5 million to a Republican super PAC.
Rivals are pointing to his fortune to suggest the Hyatt hotel heir is out of touch with average voters.
Billionaire Tom Steyer, who recently ran ads calling for President Trump's impeachment, won't run for office himself.
Taxpayers there may have the least to gain from House proposed income-tax cuts.
The campaign has no contribution limits and is expected to be one of the nation’s most expensive governor’s races.
Counties that backed him would get less than a third of the relief that would go to counties won by Clinton.