FILE PHOTO: U.S.Senator Mitt Romney (R-UT) speaks at a news conference about the Tobacco to 21 Act, which would raise the minimum age to buy tobacco products and e-cigarettes to 21, on Capitol Hill in Washington, U.S., May 8, 2019. REUTERS/Aaron P. Bernstein

WASHINGTON (Reuters) - U.S. Senator and former Republican presidential candidate Mitt Romney said on Friday it was “wrong and appalling” for President Donald Trump to push other nations to investigate former Vice President and Democratic presidential frontrunner Joe Biden.

“When the only American citizen President Trump singles out for China’s investigation is his political opponent in the midst of the Democratic nomination process, it strains credulity to suggest that it is anything other than politically motivated,” Romney said on Twitter. “By all appearances, the president’s brazen and unprecedented appeal to China and to Ukraine to investigate Joe Biden is wrong and appalling.”