Not unusual but still significant. Paul’s delivered his own SOTU rebuttal each year since joining the Senate. The Tea Party Express has sponsored a SOTU rebuttal each year during the same period, with Michele Bachmann and Herman Cain having done the honors in 2011 and 2012, respectively. The news here isn’t that they’re hooking up, it’s that someone of Paul’s national prominence and ambition is upstaging another nationally prominent, ambitious colleague at a moment when the party’s trying to leave him alone in the spotlight.

This rivalry’s been brewing for awhile in various ways but I can’t recall a clearer expression of it than this.

Paul will make his remarks soon after Sen. Marco Rubio, R-Florida, wraps up the GOP response Tuesday night, a Paul spokeswoman confirms to CNN.

“We are giving a voice to the tea party movement when the mainstream media and the Republican establishment wants to write us off as dead,” said Amy Kremer, chairman of the Tea Party Express…

“We expect many of our supporters and many of Rand Paul’s supporters, freedom loving, liberty loving Americans to be there because this is our time to be heard,” Kremer said. “We are proud that Marco Rubio is giving the official Republican Party response because he is a tea party conservative and one of our own. But the Republican Party doesn’t necessarily speak for all conservatives and the tea party movement has its own voice and this is our chance to be heard.”

The temptation is to call Rubio the loser in this deal because he’s being upstaged. Is he, though? He’s been inching away from the tea-party label since literally the moment he became a senator. According to a CNN poll taken shortly after the election, the TP’s favorable rating is 32/50. Part of the reason he’s taken up immigration reform enthusiastically is because it lets him show centrists ahead of 2016 that he’s not the “hardline conservative” or whatever that he was sporadically billed as being circa 2010. Having Paul deliver the “official” tea-party SOTU response only underscores that. You can see both of their 2016 primary strategies shaping up here: Paul will run to the right while he tries to build credibility with centrists and Rubio will run a bit further to the center while he tries to maintain his credibility with the right. (Kremer’s approving mention of him in the excerpt suggests he’s doing okay with that — so far.) The real losers here are Paul Ryan and Jindal, who risk being marginalized if the party starts to get caught up in a Rubio/Paul rivalry.

Exit question: In what meaningful ways will Paul’s “tea party” address sharply differ from Rubio’s official GOP response?