Bernie Sanders slams Joe Biden's record as the former vice president blows past him to become the 2020 frontrunner

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Sen. Bernie Sanders participates in a reenacted swearing-in with his wife Jane O'Meara Sanders and then-Vice President Joe Biden in the Old Senate Chamber at the US Capitol on January 3, 2013 in Washington, DC.

• Sen. Bernie Sanders is seeking to contrast his political record to former Vice President Joe Biden in the 2020 Democratic primary race. 
• Sanders in two separate CNN interviews went after Biden's past stances on trade and foreign policy. 
• Biden hopped in the 2020 race last Thursday and held his first rally in Pittsburgh, Pennsylvania, on Monday.
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Sen. Bernie Sanders is launching a new series of attacks against Joe Biden as the former vice president opens up a big polling lead in the 2020 Democratic primary.

In two different CNN interviews over less than 24 hours, Sanders criticized Biden's policy positions and argued that Democratic voters will see a clear difference when they "take a look at my record versus Vice President Biden's record." 

Sanders pointed to policies and legislation that he stood against that Biden supported, such as the North American Free Trade Agreement (NAFTA) and the invasion of Iraq in 2003.

"Joe and I have very different pasts," Sanders said Tuesday.

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On Monday, Sanders was asked if he's concerned by the level of support Biden has already received from unions like the International Association of Fire Fighters less than a week after declaring for 2020. The Vermont senator suggested that he was not concerned with Biden in particular.

"I'm running against, I think, 19 other people, so I'm concerned about everybody," Sanders said.

In a separate CNN appearance on Tuesday, Sanders was asked if his campaign will be more about the contrast between him and Biden or who can best defeat President Donald Trump.

The senator said "both," adding that he will do everything he can to take down Trump whether he's the Democratic nominee or not. Sanders said he'd support Biden if he ends up winning the nomination. 

"What I want to see in the Democratic primary is not personal attacks. What I want to see is an issue-oriented campaign," Sanders told CNN's Brooke Baldwin.

Until Biden hopped in the race last Thursday, Sanders was pegged as the frontrunner among declared candidates with strong poll numbers and fundraising. But Biden was still at the top of many national polls throughout the early part of the 2020 race, despite not formally entering the campaign. 

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And new polling from CNN shows Biden blowing past Sanders, giving him a lead of more than 20 points over the Vermont senator - who stands as his nearest contender. 

Biden also raked in more money than Sanders did in the first 24 hours of his campaign, raising $6.3 million to Sanders' $5.9 million.

It's still early, but Biden is off to a flying start and is the most serious challenge Sanders has faced along the campaign trail yet, which means the senator's efforts to contrast himself to the vice president might escalate in the weeks to come.