Presidential frontrunner Joe Biden told reporters that he would refuse to testify voluntarily if the Senate called him to do so in their impeachment hearings.

Peter Doocy of Fox News asked the former vice president of the possibility of being called to testify.

"If there's a Senate impeachment trial, they might want to call you as a witness is that something where you would appear voluntarily?" asked Doocy.

"No I'm not going to let them take their eye off the ball," responded Biden.

"The president is the one who has committed impeachable crimes and I'm not going to let him divert from that. I'm not gonna let anybody divert from that," he added.

Democrats have begun an impeachment inquiry based on the accusation that the president withheld military aid from Ukraine in order to pressure them to investigate Joe Biden's influence in their country.

Allies of the president have defended him by saying that there was enough evidence to seek an investigation into decisions Biden made as vice president that could have benefited his son, then a consultant at a Ukrainian energy company.

Biden did not add whether he would answer to a subpoena if it were issued by Senate lawmakers.

"And uh, like you've heard me say a lot of times, if he's worried about corruption, I've released 21 years of my tax returns," Biden concluded.

Here's the video of Biden's refusal: