What exactly would convince you that he was working with the WH and his own party on this issue? Oh, I don't know. All I have is press releases like this one, that conclusively proves that he's not interested in working with them.
These PR salvos are great for fundraising, but at the same time they pretty much guarantee that Tancredo will be on the outside looking in.
Working with the WH on this issue means one thing: Assenting to allowing illegals to stay and get on a path to citizenship. What meaningful concessions could one expect from the WH on this issue?