San Francisco — A leading Florida Democrat looked at the coming race against President Reagan and tried to explain just how tough it will be: ''I don't know if we could carry Florida for Mondale even if (former Gov.) Reubin Askew were on the ticket as his running mate,'' he said.
Later, a Florida delegate, interviewed on the Democratic convention floor here, put it another way: ''I'm afraid the Mondale-Ferraro ticket will be crushed so badly in Florida that people afterward will be feeling sorry for their families.''
Democrats, who are expected to make Walter Mondale their standard-bearer here today, know they have a hard, uphill road ahead of them. The newest polls - pitting Reagan-Bush against the new Mondale-Ferraro team - show just how steep that road is.
A Gallup poll, released at midweek, puts Reagan-Bush ahead 53 to 39. Among women, the margin is close: 45 to 43. But male voters at present give the GOP a staggering margin of 25 percentage points (59 to 34). Gallup analyst Jim Shriver says: ''The gender gap in this poll is as great as anything we've seen.''
The Gallup numbers are supported by another poll this week from the Garth Analysis of New York City. Garth's findings: an almost identical Reagan-Bush lead, 52 to 39.
Most discouraging for Democrats, both Gallup and Garth find that, at least so far, the addition of Geraldine A. Ferraro to the ticket has done very little to boost Mr. Mondale's stock.
Both found that adding the Queens, N.Y., congresswoman to the ticket was essentially ''a wash'' - that is, it makes very little overall difference. Garth reports that Mondale picks up 3 percent more of the women's vote with Ms. Ferraro at his side. But at the same time, he loses 5 percent of the men to Mr. Reagan.
To illustrate further how far behind the Mondale ticket will be at the start of this contest, private Republican polls show Mondale ahead at present in only four places - Maryland, West Virginia, Hawaii, and the District of Columbia. The GOP polls are generally confirmed by independent studies.
The job ahead for Mondale-Ferraro, however, involves electoral votes, not political polls. US presidential races are really 50 separate elections in the states. Mondale must find a way to put together enough states to gather a total of 270 electoral votes needed for victory.
Can he do it? Political wise man Robert Strauss, a former Democratic chairman , says he looked state by state recently, and he thinks it's possible - but not easy. Mondale strategists, headed by campaign manager Bob Beckel, have been making similar calculations in recent days.
When analyzing electoral prospects, planners often divide the country into four parts: the South (largest of the regions, with 155 electoral votes); the East (135 electoral votes); the Midwest (137); and the West (111).
The West, as usual, looks grim for Democrats. This has been Republican country for a long, long time, and it probably won't change this year. In some states, the Reagan lead is nearly 2 to 1. and in Utah a June poll for the Salt Lake City Tribune found Reagan ahead 70 to 22. Mr. Strauss says there's at least some hope, however, for Mondale-Ferraro in Oregon and Washington State. And Mondale is favored in Hawaii.
The South also looks cloudy. Explains an analyst: ''You've got two 'frost belt' liberals looking for votes in the Sunbelt.'' The Reagan team exudes confidence about Dixie. Democrats hope that new black voters will give them at least a few victories in such states as Louisiana, Arkansas, and Mississippi.
The Strauss scenario for victory depends primarily on very strong showings in both the Northeast and Midwest. If the South proves to be infertile ground for Mondale - a likely possibility, according to several delegates at this convention - then Democrats will essentially need to sweep the Northern tier of states.
The Garth study finds that Ms. Ferraro does seem to help in the Northest (a four-point gain), but may actually hurt with more-conservative Midwesterners (a six-point drop).
Even Republicans concede that Ms. Ferraro will probably lift the Democrats in New York State and next-door Connecticut. But they insist that Reagan is still very much in the running in New Jersey, Pennsylvania, and just about everywhere else in the Northeast.
In the Midwest, the GOP again concedes nothing. At least one poll is reported to show Reagan leading Mondale in his home state of Minnesota - a situation that , if true, will almost certainly change, Republicans admit.
If the race does tighten up, analysts say the election could hinge on several ''battleground'' states where everything could be won or lost.
At the top of just about everyone's list are two giants: Illinois and Texas. Both have been pivotal in the past.
Next are California (likely for Reagan) and New York State (a must for Mondale).
Pennsylvania and New Jersey are also key swing states, as are Michigan and Ohio.
It is Mondale's poor prospects in the South that could make the election a Reagan runaway. Analysts recall that four years ago, despite a native Southerner on the ticket, every state in Dixie except Jimmy Carter's own Georgia voted for Reagan. They wonder if Mondale can seriously expect do any better.
Democrat Strauss, staunchly upbeat, concedes that victory will be difficult, but is possible if three things happen:
* The convention ends harmoniously.
* The Mondale-Ferraro ticket proves to be effective.
* Voter registration drives are successful.
Even if Democrats are able to pull closer to Reagan in the popular vote, however, Strauss concedes the race could still end in an electoral landslide for Reagan.