U.S. Sen. David Vitter told supporters Monday that he raised $1.4 million in 20 days since announcing his gubernatorial run.

“I was very hopeful about what folks’ reaction to that decision would be. But I have to say — with real humility and enormous thanks — that my very hopeful expectations were FAR surpassed,” he wrote in an email.

Vitter, R-La., announced in late January that he will run for governor in 2015. On the Democratic side, state Rep. John Bel Edwards, of Amite, also is running. Lt. Gov. Jay Dardenne, a Baton Rouge Republican, said he intends to run. Another possible candidate is Republican state Treasurer John Kennedy.

The race already appears primed to be expensive. Because Gov. Bobby Jindal cannot seek a consecutive third term, the race will be wide open for the first time in eight years.

Kennedy let it be known last month that his campaign war chest totals $3 million. He could run for re-election or for governor. He had $2.3 million on hand before he even started collecting contributions in 2013.

Weeks later, Dardenne filed his campaign finance report with the Louisiana Board of Ethics. The report shows he has $1.2 million in the bank.

Edwards has not detailed his numbers from 2013. He had $37,315.34 in his campaign bank account at the start of last year.

A third-party Super PAC, The Fund for Louisiana Future, is collecting more cash for Vitter’s gubernatorial campaign. The fund raised $1.5 million last year, adding to the $1.4 million Vitter raised on his own.

Vitter told supporters that he is aggressively mounting a campaign by raising money, assembling a grassroots team in every parish and talking to experts.

“This is just the start. We continue to rely on your help,” he said in his email to supporters, asking them to volunteer and contribute money to his campaign.