WASHINGTON -- Only three Republican presidential candidates are worth any money -- campaign money, that is.

Mitt Romney, Rick Perry and Ron Paul have banked millions, but the other GOP candidates are struggling or broke, putting their candidacies in question four months before the first nominating contests take place.

Ahead of a critical fundraising deadline Friday, all the GOP's contenders are furiously courting donors in Texas, Georgia, Washington and elsewhere.

It's a last-minute attempt to pick up cash before they file a three-month summary that will measure one aspect of the financial strength of their campaigns.

The candidates' own cash is just part of the picture because, this year, outside groups are allowed to raise and spend unlimited amounts of money to back specific candidates.

And allies of Romney, Perry and Paul all have formed so-called SuperPACs to help their preferred candidates win the nomination.

That money aside, Romney is likely to post the strongest fundraising numbers, although he is unlikely to match the $18 million he raised in the first three months of the year.

Perry donors claim he could hit $10 million, raised since he entered the race last month. His advisers dispute that.

They are lowering expectations either so Perry's haul looks more impressive when it's announced, or it's an indication that the GOP front-runner hasn't seen a flood of money accompany the huge dose of enthusiasm he initially generated.

Paul's campaign asked supporters to celebrate the Texas congressman's Aug. 20 birthday with a donation -- and they gave him $1.6 million on that day alone. It's a pattern for Paul, who can seemingly turn on the money spigot when he needs to.

The rest of the field lags far behind.

Jon Huntsman recently had to write himself a half-million dollar check to keep his campaign afloat. Michele Bachmann spent so much money in Iowa in August to win a statewide test vote that her web videos look more amateurish than professional now.

Newt Gingrich is still mired in debt. Herman Cain has loaned himself hundreds of thousands of dollars so he can keep running, and Rick Santorum's team acknowledges that he is barely scraping by.