Guy Verhofstadt has become leader of the Liberal group, ALDE, in an unopposed contest after UK MEP Diane Wallis dropped out of the race at the last minute. ALDE is the third largest group in the European Parliament after the EPP and PASD.
Politically it means that if he decides to challenge Barroso for the Commission Presidency (it's unlikely since he would need the support of the EPP, and the - even less likely - support (or acquiescence) of the Council to manage it) he may have a stronger base in the ALDE and would be part of the Presidents of the EP who will decide on whether or not to put Barroso's second term to the vote in July. This is all a big stretch, though, but if the Commission Presidency vote is delayed to the autumn, then Barroso's candidature enters dangerous waters and it would give any Parliamentary challenger time to gather support.
At this point, and even if the vote is deferred, the most probable scenario is that Barroso will be re-appointed, and the Liberals or the PASD will win a half-term of the European Parliament Presidency.
It will be interesting to see how Verhofstadt will work in the EP (and if he'll use much of his group's speaking time. Will he try to make the Liberals a more coherent group, and will he work towards a coherent European campaign for the next elections (though it should be noted that ALDE consists of 2 Europarties), and how would he go about it?