Mike Bloomberg’s presidential campaign is in the process of reserving TV ad time in the states that will vote on March 3, according to two sources familiar with the matter.

The sources said the campaign is planning to begin the ad blitz on Monday. One source said the campaign was looking to book airtime for a 60-second spot in 20 to 30 markets across the country, and that the buy was at least $15 million — a massive amount. The other source said the buy was expected to last for one month, at 1,000 rating points per week.

Advertising Analytics, a tracking firm, reported Friday afternoon that Bloomberg’s buy had exceeded $31 million — breaking a record for political ad spending in a single week. The firm reported that the buy would last nine days, from Nov. 25 through Dec. 3. Medium Buying, another tracking firm, reported on Friday morning that Bloomberg was reserving time in 29 states — going well beyond the states voting on March 3.

A spokesperson for Bloomberg declined to comment.

The former New York mayor filed paperwork on Thursday with the Federal Election Commission to launch his campaign. However, his advisers cautioned that he still had not made a final decision on whether to run. An announcement is expected soon.

Bloomberg’s team has said he will skip the first four primary states — Iowa, New Hampshire, Nevada and South Carolina — and focus instead on Super Tuesday. The 14 states that will vote on March 3 include the two largest, California and Texas, and together represent about 40% of the U.S. population. Bloomberg has already filed to appear on the ballot in three of the March 3 states: Alabama, Arkansas and Texas.

The Associated Press reported Wednesday that Bloomberg also plans to spend $15 million to $20 million on a voter registration drive in five key battleground states. That campaign would be separate from Bloomberg’s run for the Democratic nomination. In addition, Bloomberg has said he will spend $100 million on digital ads attacking President Donald Trump during the primary season.

Bloomberg would enter a crowded Democratic field, which already includes 17 other contenders. Deval Patrick, the former governor of Massachusetts, just announced his own candidacy last week. Two polls released this week showed Bloomberg at just 3% support nationwide, about even with businessman Andrew Yang.

But with a net worth of $53 billion, Bloomberg has the resources to make himself better known.

On Friday afternoon, Sen. Bernie Sanders blasted Bloomberg’s multi-million dollar ad buy.

“I’m disgusted by the idea that Michael Bloomberg or any other billionaire thinks they can circumvent the political process and spend tens of millions of dollars to buy our elections,” he said in a statement. “If you can’t build grassroots support for your candidacy, you have no business running for president. The American people are sick and tired of the power of billionaires, and I suspect they won’t react well to someone trying to buy an election.”

This story has been updated.