2016 Postmortem

First, it is far from clear that an objection based on the claim that the vote was "rigged" in a particular state provides an actionable basis for Congress to reject an elector (or slate of electors). That's because Federal law provides that if a state, under its established statutory procedure, has made a “final determination of any controversy or contest” relative to the presidential election in the state, and if that determination was completed under this procedure at least six days before the electors were scheduled to vote (i.e. December 13, 2016), such determination is to be considered “conclusive” as to which electors were appointed on election day (3 U.S.C. §5).

Second, even if the law permits the Congress to consider an objection based on alleged vote rigging, upholding an objection requires a majority vote in both the Senate and House. If only one chamber upholds the objection, the objection fails. The chances of getting the Republican majority House and the Republican majority senate to throw out the electoral votes of enough states to deny Trump the required 270 are basically zero. Keep in mind that Republicans were elected to Congress in those same states and the Repub party isn't going to anything to cast doubt on the validity of the election Repub members of the House and Senate.