Five weeks ago, this might have been a game changer.  Is this a case of too little, too late?

Atlanta businessman and former presidential candidate Herman Cain endorsed Newt Gingrich Saturday night at a West Palm Beach Country Republican gathering after two months of wavering on whether he would offer his support to a fellow candidate.

The endorsement comes just three days before the crucial Florida primary, by far the largest state to vote so far in the GOP sweepstakes, and could help Gingrich energize tea party support. Gingrich campaign has flagged since his upstart, double-digit victory over front-runner Mitt Romney in the South Carolina primary a week ago.

“I had it in my heart and mind a long time ago” to endorse Gingrich, Cain said in a surprise appearance at the dinner. “Speaker Gingrich is a patriot, Speaker Gingrich is not afraid of bold ideas, and I also know that Speaker Gingrich is … going through this sausage grinder. I know what this sausage grinder is all about. I know that he’s going through this sausage grinder because he cares about the future of the United States of America.”

It seems a curious time for a Herman Cain endorsement.  Newt could have most used this in Iowa to combat the tough negative advertising, and to rally Tea Party support in a state where it might have made a big difference.  Alternately, Cain could have endorsed in South Carolina when Gingrich began his second surge in the polls, or perhaps just after when the race shifted to Florida and Gingrich took the polling lead.  Endorsing over a weekend with just a couple of days left before the primary vote — in a state where hundreds of thousands of ballots have already been cast — seems unlikely to change the tide of the Florida primary.

Two polls out today show that tide moving strongly in favor of Mitt Romney.  First we have Rasmussen, which shows Romney with a 16-point lead:

Former Massachusetts Governor Mitt Romney has opened a double-digit lead in Florida as the perception grows among Republican primary voters that he is the strongest general election candidate against President Obama. The state’s GOP Primary is on Tuesday.

The latest Rasmussen Reports telephone survey of Likely Florida Republican Primary Voters, conducted Saturday, shows Romney up by 16 points with 44% support. Former House Speaker Newt Gingrich is a distant second at 28%.

These figures reflect a significant turnaround over the past week. Last Sunday, just after his big win in the South Carolina Primary, Gingrich led Romney by nine.  By the middle of this past week,  Romney was back in control with an eight-point advantage. Despite all the ups and downs, the results today are very similar to polling results found in Florida three weeks ago, coming off Romney’s decisive victory in the New Hampshire Primary.

Next we have Mason-Dixon’s poll for the Tampa Bay Times, which shows much the same momentum:

Mitt Romney needed Florida to resuscitate his campaign after a South Carolina routing, and on Tuesday, Florida is poised to deliver big.

A new Tampa Bay Times/Miami Herald/Bay News 9 poll found Romney easily beating Newt Gingrich among likely Republican primary voters, with 42 percent support to Gingrich’s 31 percent. Rick Santorum trails with 14 percent, followed by Ron Paul at 6 percent.

What looked like a neck-and-neck race at the start of last week quickly shifted in Romney’s favor as he and his allies drowned Gingrich on Florida TV and the former House speaker turned in two listless debate performances.

Romney leads in every region of the state — and by 16 percentage points in Tampa Bay. The two Republican front-runners are closest in conservative North Florida, where Romney has 36 percent support and Gingrich 31 percent.

With this large a lead, the internals are not exactly critical, but there are a couple of points to note.  Romney leads women as he has throughout this primary, this time by 15, but now he also leads men — by 16.  Romney now leads all age demos and wins a clear majority of seniors.  Gingrich leads among self-described “very conservative” Republicans, but now only by six, 38/32, while Romney takes a majority of “somewhat conservative” voters, 52/24.  Gingrich also leads among Tea Party adherents, but only by 3 points, 38/35.

On the critical issue of electability, Romney has prevailed mightily.  He gets the nod over Gingrich as the best opponent to Obama by almost 2-1, 53/29.  He also has a double-digit lead on the question of which would be more likely to keep campaign promises, 38/21, perhaps a backfire from Gingrich’s moon-base promises to Floridians — a case where pandering fell victim to reality.  And perhaps the most worrisome for Gingrich, the percentage of people sure of their vote has risen to 74% — and the demos in which Romney leads tend to be most certain: seniors 80%, somewhat conservative 73%, and “other” 79%, where Romney leads 45/25.

Absent a game-changer, Romney appears poised for a double-digit victory in the first closed primary of the season, just as the nomination race starts splitting into the simultaneous contests that favor Romney’s organization.