Special first, then November replacement
If DeLay resigns from Congress, then a special election will be held. At this point, it looks like the candidates will be:
David WallaceThey will all run against each other. If no candidates gets over 50%, then the top 2 will go to a runoff. That winner will be Congressman until January. In January, whoever wins the November election (probably, but not necessarily the same person) will be the Congressman.
With a crowded field, it's unlikely that anyone else will run who has a chance of winning. The only person who I could see considering it right now would be state Sen. Kyle Janek, but my guess is that he will pass. I could definitely be wrong, that's my very first guess. So there's a reasonable probability that this will be the field. But again, that's just an initial guess.
[UPDATE: Elam thinks that this race could get very crowded indeed. He might be right.]
Presumably, if the special election winner is a Republican (which is very likely) then the party will make the special election winner the nominee.
This is not necessarily so, however. It's possible although unlikely that the Republican party might choose someone else to run against Lampson in November. Republicans will choose the November nominee by
1) the county chair of each county that is wholly situated in theSee Texas Election Code Section 145.038. In other words, either Kronberg or Wallace got the law wrong. But they were close.
(2) one precinct chair from each county that is only partly situated in
the district, elected by and from among the precinct chairs of the
precincts in that part of the county.
However, if the district executive committee fails to nominate someone, then the state executive committee (SREC) will choose the Republican nominee who will face Nick Lampson in November. Texas Election Code Section 171.054.
UPDATE: Elam reports that Fort Bend County GOP Chair Eric Thode is saying that DeLay isn't planning on resigning for awhile. Conceivably, if DeLay resigns late enough, both the special election and the general election could be held on the regular election date.
My guess is that there will be a special election before June. But we'll see in the next few days.
Note: I intended to be asleep a few hours ago, so if I don't make sense, you'll know why.