Senate Republicans Monday revived an investigation into whether Ukrainians coordinated with the Democratic National Committee to provide damaging information on President Trump ahead of the 2016 election.

Senate Finance Committee Chairman Chuck Grassley of Iowa and Homeland Security Committee Chairman Ron Johnson of Wisconsin wrote to Attorney General William Barr that they also want to know whether the Justice Department has information from Ukrainian prosecutors that contradicts former Vice President Joe Biden’s explanation for threatening to withhold $1 billion from the country.