They would, most definitely, not. And if it boils down to Samaras vs Tsipras, I'm not at all sure who their defectors would favor. AnEl voters, seem to like Tsipras, and like what he is now doing to the system...
And there are three factors to consider: where the PASOK voters would turn to, what happens with the strong pressures by SYRIZA on KKE's base (They were polling at 13% a few months ago) and how many of the non-voters (approximately 17-18% in real terms) show up. Plus I'm not sure that the dissafected young people who voted for the Nazis as a spoiler vote would shift to the conservatives... So we would have be a ball game... If Hollande however shows up with Tsipras and promises say to "preserve the integrity of the Eurozone above all else" or something equally reassuring, it will be a landslide...

The road of excess leads to the palace of wisdom - William Blake