The last week has been less than kind to Sen. Marco Rubio (R-Fla.). We learned last Friday that the right-wing lawmaker has insisted for years that his parents fled Castro’s Cuba, but documents prove that Rubio’s mother and father left the island in 1956, years before Castro’s takeover.

The senator continues to insist that he’s the son of “exiles” — even making a distinction between his family’s history and that of “immigrants” — but the St. Petersburg Times reported yesterday that this isn’t true, either. Rubio bases the “exile” claim on the notion that his parents intended to return to Cuba, and couldn’t because of the Castro regime, but the newspaper uncovered materials showing that Rubio’s parents sought visas to permanently relocate to the United States three years before Castro.

MSNBC had a good segment this morning on the distance between reality and Rubio’s rhetoric, including the latest evidence that the senator must have known at least some of his claims were false when he was making them.

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The Washington Post‘s Peter Wallsten, interviewed in the MSNBC segment, also considered today whether Rubio’s viability as a national figure — he’s assumed to be at the top of the Republican ticket’s short-list in 2012 — has taken a serious hit.

…Rubio’s role in recent controversies, including a dispute with the country’s biggest Spanish-language television network and new revelations that he had mischaracterized his family’s immigrant story, shows that any GOP bet on his national appeal could be risky.

Democrats had already questioned whether a Cuban American who has voiced conservative views on immigration and opposed the historic Supreme Court nomination of Sonia Sotomayor, the first Latina justice, could appeal to a national Hispanic electorate of which Cubans are just a tiny fraction but have special immigration status. And Rubio’s support in Florida among non-Cuban Hispanics has been far less pronounced than among his fellow Cubans.

I continue to think Rubio’s record of falsehoods would be especially problematic if Mitt Romney is the nominee. Could the GOP ticket afford two candidates for whom honesty and consistency has proven to be a long-standing problem?

American Bridge 21st Century, meanwhile, released a new document last night, showing that Rubio had “at least 20 opportunities” to correct the record about his bogus family claims. He chose not to.

The media and the Republican Party have positioned Rubio as the rising star with limitless potential, but the bloom is clearly off the rose.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.