More than $63 million has been spent on advertising on radio and television blasting Donald Trump since the Republican front-runner won the New Hampshire primary in February — nine times what was doled out beforehand.
In the first three days of this week alone, forces trying to block Trump spent $7.6 million on ads, according to an analysis by
ABC News, representing two of every three ad dollars spent by Republicans.
"This means anti-Trump advertising increased 900 percent between the first two weeks in February and the days before the crucial March 15 contests in Florida and Ohio," the report said.
Despite outspending Trump by three times so far, the front-runner continues to rack up wins in state primaries and caucuses.
"The situation is fluid regarding how these stop Trump campaigns will move forward," a close to the anti-Trump efforts told ABC News. "Decisions will be made over the coming days as to the best use of resources: continue a public advertising campaign to further expose Trump's record and slow his primary momentum or work on a delegate strategy at the GOP convention."
ABC News analyzed data from CMAG/Kantar Media.
The biggest spender so far in the current cycle is the Conservative Solutions PAC, which backed Florida Sen. Marco Rubio, who dropped out of the race on Tuesday.
The group has spent nearly $20 million, ABC News reports.
The next is the Right to Rise USA super PAC, which backed Jeb Bush. The former Sunshine State governor quit the race last month.