(CNN) -- With just days to make last-minute pitches to voters in two dozen states, the presidential candidates are pouring millions into television advertising before Super Tuesday.
Sen. Hillary Clinton emphasizes economic issues in one of her television ads.
February 5 is virtually a national primary day, and the stakes could not be higher for the candidates. Thousands of delegates are up for grabs from coast to coast, and voters from the delegate-rich states of California, New York, Illinois and New Jersey will be among those heading to the polls.
Spending on political ads in the Super Tuesday states alone could reach an unprecedented $20 million, the Campaign Media Analysis Group estimates.
"The spending will set a record for Super Tuesday states because of the enormity of the contest," said Evan Tracey of TNS Media Intelligence/CMAG. "We've never had 20-plus states in one day in a primary contest."
A vast majority of the spending -- nearly 90 percent -- is being done by the two remaining top-tier Democratic candidates: Sens. Barack Obama and Hillary Clinton. Both campaigns are well funded. On Thursday, they reported that they both had roughly $18 million in cash at the end of December to spend during the primary season, according to the campaigns' reports to the Federal Election Commission.
The Obama campaign also announced Thursday that it raised $32 million in contributions in January.
Flush with campaign funds, Obama spent $4 million on television advertising the last week of January, much of it going to advertising in the biggest Super Tuesday prize: California.
One of the ads the Obama campaign is airing features images of former President John F. Kennedy and of his daughter, Caroline Kennedy, who endorsed the Illinois senator this week. Caroline Kennedy's uncle, Massachusetts Sen. Edward Kennedy, also has endorsed Obama.
Not to be outdone, Clinton spent over $3.5 million on television advertising the last week of January, CMAG estimated. Like Obama, the New York senator spent much of her money on California advertising. Clinton focuses on economic issues in her ads and, in one commercial, features the phrase "Solutions for America."
Clinton's ads also emphasize her experience on the national stage. In an ad titled "Steel," the narrator says "she has endured nearly two decades of intense scrutiny. That she survives and thrives speaks to qualities that would serve a president well."
The Republican presidential candidates are operating with much smaller amounts of cash in the bank than the Democrats and, thus, are spending less on television advertising. At the end of December, former Massachusetts Gov. Mitt Romney had roughly $2.5 million in the bank, while Sen. John McCain had nearly $3 million, according to the campaigns' reports to the FEC.
"All the campaigns right now on the Republican side are essentially out of money and can't carry their message," Tracey said.
McCain and Romney, however, both should have the funds necessary to buy some television advertising before Tuesday, if not at the level of the Democrats.
McCain's fundraising picked up after he won the New Hampshire, South Carolina and Florida primaries, and Romney loaned his own campaign $18 million in the last quarter of 2007, bringing the total amount he has loaned his campaign to $35 million.
McCain emerged as the party's clear front-runner after winning the Florida primary Tuesday and has significant momentum going into next week's primaries. Super Tuesday could play a critical role in determining whether Romney will be able to challenge McCain for the Republican nomination.
"Obviously, things are still in play and things are very much going to be decided on February 5," said Ken Goldstein, a political science professor at the University of Wisconsin-Madison. "This is his last chance to derail McCain."
On Thursday, the McCain camp made a "significant" ad buy that will put the Arizona senator's television commercials on the air in some 20 states before Super Tuesday, campaign sources told CNN. The ads would run in every Super Tuesday state except Utah, the sources said.
The cost of the advertising would run in the "seven figures," the sources said, but they refused to give a specific amount.
The McCain ad that will air is titled "True Conservative" and touts the senator's "commitment to conservative principles on economic, social and national security issues as well as his readiness to lead as commander-in-chief on Day 1," the campaign said.
McCain spent close to $2 million on ads in Florida alone the week before that state's crucial primary.
On Thursday, Romney's campaign also announced it will purchase time to air television advertising in California and in other Super Tuesday states. The ad buy is estimated to cost between $2 million and $3 million, the campaign told CNN.
In the television ad running in California, titled "Experience Matters," Romney tries to get conservatives' juices flowing by attacking Clinton for not having the experience "to run the largest enterprise in the world" and includes video of Romney extolling his own leadership experience.
"I have spent my life running things. I've learned how to run a business. I've learned how to run a state. I ran the Olympics. In each case, I've brought change," Romney says in the ad. "And if there's ever been a time we needed change in Washington to bring strength to America, it's now." E-mail to a friend
CNN's Jason Carroll, Tasha Diakides, Bill Schneider and Dana Bash contributed to this report.