St. Louis, Missouri (CNN) Former Vice President Joe Biden has launched his largest ad buy so far in the 2020 election, investing $12 million on advertising that will air ahead of the March 10 and 17 primaries, a Biden campaign aide confirmed to CNN.

The two ads, first reported by the Associated Press , will play on digital platforms YouTube, Facebook and Instagram and in television markets in Michigan, Missouri, Mississippi, which vote on March 10, and Florida, Illinois and Ohio, which head to the polls on March 17. The former vice president is set to campaign in Missouri and Mississippi this weekend and heads to Michigan and Ohio early next week. He is expected to hit all six states before March 17.

"Always," a new ad, responds directly to Biden's primary rival Sen. Bernie Sanders, who has ramped up his criticism of the former vice president on the campaign trail and recently launched an ad in the upcoming primary contests hitting Biden on his social security record. "Bernie Sanders goes on the attack," a narrator says. "Politifact has called the Sanders campaign attacks false." It continues to defend Biden's record on social security. "Joe Biden has always been a strong supporter of social security. Biden will increase Social Security benefits and protect it for generations to come."

"Negative ads will only help Donald Trump," the narrator ends. "It's time we bring our party together."

While Sanders has hit Biden on his social security record for months, the attacks have increased since the primary has narrowed to a two-man contest after Biden emerged victorious on Super Tuesday , winning 10 out of 14 states that day.