Wasserman, a polling analyst with Cook Political Report (but has a disclaimer on his personal account), made a call in ME-02 (see below) in favor of Democrat Golden. I reply-tweeted that he was dead wrong--not about the likely outcome, but the timing (no acknowledgement).
Election rules vary by state, and for this discussion we'll focus on single-winner; some states have jumbo primaries/general election runoff (multiple party candidates) e.g., LA and CA, a few require require a majority, e.g., GA, often requiring a runoff between top percentage candidates; and probably most s plurality system, where the top choice by votes wins, regardless of percentage level. There may be nuances or combinations of these (see here for a drill-down map of state election systems).
In some states mail-in ballots may be accepted for a limited number of days after Election Day provided postmarked by Election Day; in a large percentage of states, the mail ballot must be received on or before Election Day. I haven't seen many statistics on legal ballots received past elections, but in Internet searchers I found something like 2500 in MN. I'm not saying these are unworthy but in most statewide races these are not materially relevant.or different from the overall voter population.
Two House races will be decided by RCV ranked-choice: Alaska and Maine-2. So here's how i generally works: the process stops when the lead candidate has 50%+1 or more. of the total race votes. Generally this will always be the case for 1-2 candidates..It's generally the case if the lead candidate has less than 50% there's at least a third and/or more candidate(s). Then you look at the lowest candidate (N) votes. You then redistribute N's votes based on second choices (if any and/or legitimate, i.e, you didn't vote for multiple second choices). N is now eliminated. If A has a majority now with redistributed N, A wins.. If not we then repeat the process. [Late note: I started writing this essay more than a week back. Both races had incumbent Dems close to a majority. the Maine Dem won last week and the Alaska one should be decided this week.]
So let's look at the Maine race below, likely decided Tuesday. The incumbent, a Dem, has 48.2%. Waasserman probably saw that Golden has a 3+ point lead and there's less than 2% outstanding. Poliquin has no shot at closing the gap under plurality rules. On the other hand Poliquin needs to net over 5 of Bond's nearly 7 points to win. I don't know enough of Bond's voters. If they all hate the incumbent, Polinquin has a shot. But if he doesn't get enough net Bond votes to surpass their current difference. Golden wins. The odds are not in Polinquin's favor.
Alaska is similar. The incumbent Peltola has over 47% and second place Palin is a distant second, over 20 points. But third-place Begich, although a Republican, voters won't necessarily support Palin (they didn't in the recent special election). The Republicans have paid lip service to rank red, but Palin has said she would rank Peltola over Begich--and I'm sure Begich's supporters noticed. I would be shocked to see Palin prevail..
So why RCV? The dominant plurality system has problems in our 2-party system. Let me give a couple of examples. to provide context. In 2008 primary, John McCain, to get the nomination, worked hard to reinforce his support of the unpopular Bush Administration, which was highly popular with the party base but anathema outside the base. Now he gets the nomination, but his ties to Bush are killing him in a change election year. In a more open election format, McCain could have sought to leverage his bipartisan record among independent voters. I'm not saying that would have led him to beat Obama (I think the Dems' embrace of the social welfare net in the aftermath of the economic tsunami made a Democrar a favorite over McCain's more fiscally conservative record), but a more open inclusive process would not have put McCain in the position of having to stress his partisan bona fides.
Another example is the 2016 GOP primary. I have long felt that under a RCV system Trump's hostile takeover of the GOP may well have been thwarted. In hindsight it's hard to tell, of course. The early months saw an early dominance of anti-establishment politically inexperienced candidates like Trump, Fiorina, and Carson. They were sharing like 40-60% of early polls with more conventional candidates senators and governors splitting the rest, none of them gaining more than 10-15% or so of those polled. Trump got the highest share like 25-30%, no doubt leveraging his celebrity, particularly his popular Celebrity Apprentice TV series. I think the conventional candidates felt the Trump candidacy would implode on its own and were hoping to attract Trumpkin supporters if they were personally congenial towards Trump. I remember I preferred Rand Paul but he had withdrawn by the SC primary. I wanted almost anyone but Trump; I think I ended up supporting Cruz, but I was willing to join supporters of Bush, Rubio, etc. It's hard to say but early RCV could have consolidated the fragmented field earlier.
There are no guarantees of course: activists could have pushed Trump over 50%. Trumpkins would have regarded losing an election he won a plurality as an establishment plot against him. But it would have provided less risk of a manipulated election, e.g., crossover Dems trying to back a weaker opponent, or a candidate with limited popularity beyond a minority base.
