Today marks the second-to-last day of March, so there’s really only one thing that matters in the presidential race this week: Tomorrow’s midnight first quarter fundraising deadline. All the campaigns are making their big last-hour pushes right now, with final emails going out to their lists, and finance staff, donors, and backers calling their friends to ask for more money.

This weekend’s deadline, which will have the numbers reported to the Federal Election Commission by mid-April, will be a critical early test of a candidate’s viability to compete in what will be the most expensive presidential campaign in U.S. history—of course at least two candidates, Evan Bayh and Tom Vilsack, have already been forced from the race because of money. Hillary Clinton laid the framework in an email this morning: "Until next year, when people making choices in primaries and caucuses, there may not be a bigger day in this campaign than the next 24 hours."

Hotline's political genius-in-residence Marc Ambinder this morning reports his final predictions of how much each candidate will raise:

* Sen. Hillary Clinton will raise between $23M and $30M.
* Sen. John McCain will raise between $26M and $32M.
* Sen. Barack Obama will raise between $20M and $25M.
* Ex-MA Gov. Mitt Romney will raise between $19M and $21M.
* Ex-Sen. John Edwards will raise between $13M and $17M.
* Ex-NYC Mayor Rudy Giuliani will raise between $12M and $15M.

Each candidate hopes to exceed the media's expectations and thus be seen as stronger than initially thought. Thus the campaigns have spent the last two weeks furiously lowering their own expectations while raising the bar for everyone else. As John McCain, who has raised tens of millions over the course of his political career, put it tongue-in-cheek this week on the Today Show, his fundraising is just going to be terrible: "I'm not very good at it. I hope to get better."

Of course, there’s a second much more important question that’ll be answered in these first quarter reports: How much money did the campaigns manage to save? The most expensive race also means the campaigns have been spending money a furious clip—Mitt Romney already has put ads on the air; many campaigns boast scores of staff across a dozen states or more—and there’s still ten months before any votes are cast.

Stay tuned.