(CNN) Sen. Elizabeth Warren released a new campaign ad Tuesday, hitting Michael Bloomberg in the states that vote on Super Tuesday and attacking the billionaire for his campaign spending and past support of a Republican incumbent whom Warren ousted for her Senate seat.

The Warren attack ad comes ahead of the critical March 3 contests, which account for more than a third of Democratic delegates, and at a crucial moment for the Massachusetts senator to remain viable in the crowded field. Bloomberg, too, is staking his candidacy on the states that vote on Super Tuesday and beyond. He skipped the early state nominating contests and has been focusing his resources on states that vote later in the cycle and those that will be battleground states in the general election.

"You've probably seen more ads for Michael Bloomberg than the rest of us running for president put together. Big money is powerful but it doesn't always win. I know that first-hand," Warren says, narrating the ad

"When I ran against an incumbent Republican to take a US Senate seat away from Mitch McConnell, Bloomberg endorsed the Republican and he raised big money for him. But I beat him anyway," she adds.

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