It's over for Andrew Swan. Until the results from The Pas came in yesterday, Swan had reason to fight on, since if Frank Whitehead had managed to bring his supporters with him, that would have been some 120 delegates, which would have brought him within striking distance of Ashton. It would still have been an uphill battle, but he might have been able to at least hope to overtake Ashton and see what happened on the second ballot. That hope has now evaporated, and Swan has, quite sensibly, decided to wait till next time. And I don't think we've seen the last of Andrew Swan by any means; as a (relatively) young MLA in a secure constituency, he potentially has a long political career ahead of him.
So what does this do to the race? Well, in one sense his resignation obviously helps Selinger... but he wouldn't have quit if he'd won The Pas, and Ashton winning The Pas helps him considerably. According to this article, the count prior to the meeting in The Pas was 319 for Selinger, 224 for Ashton, 70 for Swan, and 33 undeclared. I don't have the exact numbers from The Pas yet, but I think it was pretty much a sweep for Ashton, so assuming he gets all 120, and all the Swan delegates go to Selinger, this puts it at 389 for Selinger and 344 for Ashton. Given that there are a couple of huge ridings yet to come, as well as a significant number of delegates selected by the labour movement, it would be foolish to count Ashton out at this point.