COLUMBUS – Ohio Sen. Rob Portman said Monday it's wrong for President Donald Trump to ask Ukraine or China or another foreign entity to investigate Democratic rival and former vice president Joe Biden. But Portman, a Republican from Terrace Park near Cincinnati, said he doesn't see it as "an impeachable offense" and said Democrats are rushing to impeachment.

"It's not appropriate for a president to engage a foreign government with an investigation with a political opponent," Portman told reporters Monday outside the annual Ohio Defense Forum.

House Democrats have called for an impeachment inquiry against Trump following a July phone call in which Trump urged Ukrainian President Volodymyr Zelensky to investigate Biden's involvement in the firing of Ukrainian prosecutor Viktor Shokin . Shokin had investigated Ukrainian natural gas company Burisma between 2010 and 2012. Biden's son Hunter became a board member of the company in 2014.

The call prompted a whistleblower complaint alleging Trump asked a foreign government to interfere in the 2020 presidential election. Democrats had already launched an investigation into whether Trump's decision to withhold $250 million in military assistance was tied to efforts for a Ukrainian investigation of Biden's actions.

Trump has claimed that Biden, as vice president, forced out Shokin to protect his son.