U.S. 2020 Democratic presidential candidate and former Representative Beto O'Rourke speaks at the 2019 National Action Network National Convention in New York, U.S., April 3, 2019. REUTERS/Shannon Stapleton

WASHINGTON (Reuters) - U.S. Democratic presidential hopeful Beto O’Rourke raised $9.4 million in the first 18 days of his bid for the presidency, his campaign announced on Wednesday.

O’Rourke, the former congressman from Texas whose unsuccessful Senate run in 2018 garnered him national attention, collected 218,000 separate contributions, his campaign said in a statement.

The average donation was $43, his campaign said.

Like most of his Democratic rivals, O’Rourke is refusing campaign donations from corporate political action groups or lobbyists. Of the money he did raise, 99 percent came from online solicitations, O’Rourke’s campaign said.

Candidates are required by law to track and report all campaign donations. Donations collected between Jan. 1 and March 31 must be disclosed by April 15. Candidates are limited to collecting $2,800 from a single donor during the primary process.

O’Rourke’s first-quarter haul lags behind some of his other Democratic rivals who announced their candidacies earlier in the year and therefore had more time to raise funds. O’Rourke launched his campaign on March 14.

U.S. Senator Kamala Harris of California, who launched her campaign in late January, raised $12 million in the first quarter. U.S. Senator Bernie Sanders of Vermont, who began his campaign in late February, raised $18.2 million.

With such a crowded field - more than 15 Democrats have announced they are running - fundraising abilities have become an early way to prove to donors and potential supporters that a candidate is viable.

Additionally, the Democratic National Committee has said a candidate must have raised money from 65,000 different donors in order to qualify for the first debate to be held on June 26 and 27.