ALTOONA, Iowa -- Six presidential candidates spoke at the United Food and Commercial Workers forum Sunday about issues relating to union workers, but there was a focus on the impeachment inquiry and the Ukraine investigation off the stage.
Former Vice President Joe Biden said he is the reason for this discussion in the first place, as the impeachment inquiry surrounds a July phone call President Donald Trump made with Ukrainian president Volodymyr Zelensky. According to a transcript of the phone call, Trump asked Zelensky to look into corruption related to Biden's son, Hunter Biden, and his business dealings in Ukraine.
However, the former vice president has repeatedly said there is no evidence of any wrongdoing by either him or his son.
"No one, no one has indicated of any consequence that anything was done wrong or illegally by me or by my son," Biden said.
Biden was one of the last of Democratic presidential hopefuls to say he supports the U.S. House of Representative's impeachment inquiry against Trump.
"Let's focus on the problem. The problem is we have a president who violated his oath. He's invited, not just relating to me, on three occasions, he's gone to foreign governments and asked for their input in a domestic election," Biden said. "The Russians, the Chinese and the Ukrainians. There's not a single shred of evidence to suggest anything I did was wrong."
Presidential candidate Pete Buttigieg came to Biden's defense earlier in the day, saying the Biden family holds a "radically different standard" than the Trump family.
Another candidate, Sen. Kamala Harris, D-California, was asked as a former prosecutor if there is enough evidence to impeach the president. Referring to the phone call transcript, she said "we've got a confession and it doesn't take a prosecutor to see that."
Another driver of conversation for candidates Sunday was Trump's decision to withdraw U.S. forces from northern Syria, where troops had long kept peace among competing forces. This came as a Turkish invasion targeting U.S. and Syrian Kurdish allies' fight against the Islamic State expanded.
"He is the weakest president to occupy the oval office," candidate Sen. Michael Bennet, D-Colorado, said. "What he did to the Kurds is something no other president would have done, Democrat or Republican."