If Charlie Crist announces an independent bid for the US Senate today as widely expected, can anyone doubt that this will be one of the most effective political ads of the year? Marco Rubio speaks volumes by letting Crist do all the talking:

We’ve played this before, as have many bloggers and media outlets, but blanketing Florida airwaves with this ad (or a shorter version of it) will force Crist to ask a very uncomfortable question — what changed since March 28th? Neither he nor Rubio have made any policy changes during that period of time. The national GOP hasn’t changed its position regarding the race; the NRSC still has its endorsement of Crist in place. That actually makes Crist the establishment Republican candidate, at least until 5 pm ET today.

The only answer that will make sense to Florida voters is that Crist can’t get elected as a Republican in 2010. Crist was “very proud” to remain in the party of Abraham Lincoln and Ronald Reagan as long as it remained the party of … Charlie Crist. It’s pure self-interest, arguably accompanied by an impulse for self-destruction.

Update: Crist is giving “pro-rated” refunds to donors this afternoon, reports the St. Petersburg Times.

Update II:  The NRSC has removed Crist from its website, reportedly since yesterday.