I assume that hundreds of votes were cast in the election by people who were not legally entitled to register or vote: non-citizens; residents of other states; outright fraudsters using other people’s indentity to vote; casting absentee ballots for mentally incapable individuals, etc. Rather than play games in the legislature, why not file suit against the Virginia BOE, Arlington, Fairfax, and Richmond Registrars and election officials charging that they allowed illegal voting in more than enough numbers to invalidate the election. It is hard to prove who these votes were for, but that doesn’t matter, if you can show that more illegal votes were cast than the margin of victory for Herring (but show three times as many for good measure). Investigate, demand documents from all defendants, show the facts in court, demand that the November election results be awarded to Obenshein or a new election be held. Of course, all that requires two things: an honest court and actual evidence of illegal voting.
That sounds logical, but it probably doesn't work that way. We had a similar situation in Washington State a few years ago in our Governor's race. The GOP candidate sued for a Contest - the formal process to contest an election. He *proved* that their were more illegitimate votes than the margin of victory, but unbelievably this is not the standard for invalidating an election in Washington, it is that the evidence shows the election was stolen. Seeing as it was impossible to determine (in many cases) who the illegitimate votes were for the election was allowed to stand.
I don't think you can sue to overturn an election as long as you have not taken full advantage of the process given in law for setting things right.
What ever the "contest" rules are in this case are what the candidate should follow. If that results in the GOP House giving him the win, so be it. Politics ain't softball.