Usher? Jonas? Minaj? Who's Really Joining Britney's Tour?

Could Usher really be going out on the road with Britney Spears? Sounds like an April Fools Joke. Joe Jonas would seem to make a little more sense.
But after the embarrassment that was Enrique Iglesias unceremoniously bailing on a coheadlining jaunt with the "Oops!" girl earlier this week, what's a songbird to do?
E! News has learned that Spears' camp has now entered into negotiations with rising hip-hop diva Nicki Minaj to replace the Spanish crooner on the Britster's upcoming summer trek.
Given it's called the Femme Fatale tour, we'd say this is a good choice.
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"There are talks going on with Nicki Minaj about joining the tour," a source close to Spears tells E! News.
As for reports that Britney is looking to woo Usher and Joe, the insider hasn't heard anything about that. (We'd imagine getting the "Yeah!" singer would be tough unless the pop stars agreed to joint billing and she opened for him!)
Spears' rep could not be reached for comment.
The Trinidad and Tobago-born Minaj's career has been on the fast track since the release last November of her debut album, Pink Friday, which topped the Billboard 200 Chart earlier this year and has gone platinum, largely on the strength of her joint single with Will.i.am, "Check It Out."  The crooner also appeared on Saturday Night Live in January, where she performed her hits "Right Thru Me" and "Moment 4 Life," and wowed the red-carpet crowd at the Grammys with her mile-high hairdo.