Michael Bloomberg, who spent $1 billion of his own money on a failed 2020 presidential bid, will inject at least $100 million to help Democrat Joe Biden’s campaign against President Donald Trump in Florida.

The billionaire’s decision comes at a critical moment in the final 51 days of the race, with polls showing a close race in the battleground state and no financial advantage for the sitting president as voting gets under way later this month.

Trump’s initial financial supremacy over former Vice President Biden evaporated after the Republican’s campaign spent freely and Democratic fundraising surged once the party’s divisive primary ended.

“Mike Bloomberg is committed to helping defeat Trump, and that is going to happen in the battleground states,” said Bloomberg adviser Kevin Sheekey, who added that the ex-New York City mayor’s spending “will mean Democrats and the Biden campaign can invest even more heavily in other key states like Pennsylvania, which will be critical to a Biden victory.”

Even before Bloomberg’s spending, both campaigns were expecting Florida to be the most expensive state in which to campaign. It will be the biggest prize among competitive states on Election Day, offering 29 of the 270 Electoral College votes needed to win.

In-state voting by mail in Florida starts on Sept. 24, and Biden is planning his first in-person visit to Florida of the general election season on Tuesday.

Trump won the state by 113,000 votes in his victorious 2016 election, or 1.2 percentage points. He has since adopted the state as his residence and visits regularly.

Recent polls have shown Biden with a very slim margin there, gaining ground with older voters but trailing previous Democrats’ performance with Latinos. People over 65 years old make up one in five of the state’s population and Latinos make up one in four.

Trump’s re-election campaign and the Republican National Committee on Wednesday said they raised a combined $210 million in August, falling far short of Biden’s record-breaking haul of $364.5 million for the month that included both party’s televised conventions.

The strong fundraising may have allowed Biden to completely erase a long deficit in fundraising against Trump. Before the August fundraising tally, the Trump campaign reported having $300 million in cash on hand, compared with Biden’s $294 million. Neither campaign has reported a more recent figure. The figures also do not include money being spent by outside groups.

The candidates have already booked $58 million in advertisements to run between last Tuesday and the Nov. 3 election, more than any other single state, according to Advertising Analytics LLC, a market data firm.

The Republican president, who trails Biden in national opinion polls, told reporters last week that he would spend money from his own real-estate and brand-licensing fortune, if needed.

“I thought Mini Mike was through with Democrat politics,” Trump said on Twitter on Sunday. “Save NYC instead.”

Democrats had worried that Bloomberg’s promised help for the party might not come through after he abandoned his own presidential primary campaign. Some were angered by Bloomberg’s getting a prime-time speaking slot at the Democratic convention in August and said that his spending to date did little to advance his candidacy or the party’s chances.

A Bloomberg aide said the money would be used to help bring people to the polls who support Biden and communicating with Latino voters, in particular.

“This will force Republicans and the Trump campaign to shift even more of their limited resources to Florida,” the aide said.

Bloomberg won’t be the only outside actor pouring money into the race. America First Action Inc, a group that supports Trump, said last week that it would spend $12.7 million on new ads in Florida targeting Biden.

Unite the Country Inc, a similar group backing Biden, said last week that it is rolling out $1.4 million in targeted digital advertising aimed at persuading Latino voters in South Florida.