Rep. Adam Schiff said on Sunday that if an investigation finds that President Trump pressured Ukraine’s president to investigate Joe Biden’s son—in an alleged effort to find damaging information on one of his leading Democratic challengers—then impeachment is the only option. “I have been very reluctant to go down the path of impeachment... this would be an extraordinary remedy, a remedy of last resort, not first resort,” the U.S. House Intelligence Committee Chairman said on CNN’s State of the Union Sunday. “But if the president is essentially withholding military aid at the same time that he is trying to browbeat a foreign leader into doing something illicit that is providing dirt on his opponent during a presidential campaign, then that may be the only remedy that is coequal to the evil that that conduct represents,” Schiff said.

During one July phone call to Ukrainian president Volodymyr Zelensky Trump allegedly asked his counterpart eight separate times to investigate whether Biden, as Vice President, threatened to withhold U.S. aid to Ukraine unless a prosecutor who was looking into a gas company his son, Hunter Biden, was involved in was fired, The Wall Street Journal reports. The alleged phone call means that Trump is once again facing allegations of seeking political assistance from a foreign government, despite the prolonged Mueller investigation into similar accusations. Schiff has previously been reluctant to call for impeachment, telling CNN on July 25 that the only way Trump would leave office is to be “voted out.”