I think Tsipras knows exactly what he's doing -aiming to strengthen his mandate while dealing with the interecine dissidence at the same time. There doesn't seem to have been an opinion poll for a while - though I'm sure that new ones are being conducted as we speak - but Syriza's ratings at the end of last month were a pretty comfortable 40+%.
The new party is going to steal some of those brownie points of course. But as the Guardian link suggests, and Kathimerini agrees, one of the reasons for rushing into the election is to prevent Popular Unity getting its act together.http://www.ekathimerini.com/200785/arti ... -explainer
In the absence of a credible opposition Syriza is going to win the battle, but as for the war....they'll likely still need a coalition, in greater numbers than hitherto, and Lafazanis sure isn't going to be playing ball. So Alexis needs to win a lot more converts from the other existing parties, or it's going to be a numbers game.