WASHINGTON — Following Sen. Ted Cruz and Rep. Beto O'Rourke's debate Friday, O'Rourke's campaign is asking donors to raise $5 million before the end of the month.

"Obviously, this goal is very steep. It's steeper than any other goal we've set before," O'Rourke campaign manager Jody Casey wrote in a fundraising email.

If the campaign meets the lofty goal, it would be a clear signal that O'Rourke could be reporting huge fundraising numbers for the third quarter of the year. The cutoff for third-quarter fundraising is Sunday.

Politico recently reported that O'Rourke raised more than $9 million just online in August, based on federal filings.

During the second quarter of the year — a three-month period — O'Rourke raised a total of $10.4 million, and Cruz raised $4.6 million.

The challenge has credibility in part because a similar, though more modest call to action was effective in mid-August.

After Cruz released his first ads attacking O'Rourke, the El Paso Democrat's campaign raised $1.27 million in three days to counter them.

While Cruz has lagged behind O'Rourke's campaign fundraising, he is backed by several conservative political action committees and super PACs that have collectively spent around $1.7 million opposing O'Rourke, according to the Center for Responsive Politics.

The candidates will debate for the second time on Sunday in Houston.