Current polls may now show results of elections impossible this year. Bernie Sanders may be showing political trends that have yet to materialize but can still do so due to demographic change. John Kasich may show what a 2020 election looks like in the wake of a failed Democratic Presidency this time.
Polls involving Sanders (who needs to win about 70% of all remaining delegates to win the Democratic Party's nomination for President, which is the only way that one wins in a binary race) and Kasich (at best a compromise choice between Cruz or Trump supporters after several balloting failures by both, which will probably not look as good in November 2016 as it does now) may be losing current relevance. But note that I say "current". [
Bernie Sanders vs. Ted CruzBernie Sanders vs. Donald Trump30% -- lead with 40-49% but a margin of 3% or less
40% -- lead with 40-49% but a margin of 4% or more
60% -- lead with 50-54%
70% -- lead with 55-59%
90% -- lead with 60% or more
White -- tie or someone leading with less than 40%.
This is a rough estimate of how I see a 2020 election involving a Republican President who wins in 2016 but has a failed Presidency. (Really, I'd concede Utah to the Republicans but allot Georgia and Missouri to the Democratic nominee). Anybody who believes that with the states filled in as they are that the Republican nominee has a chance of winning Delaware, the District of Columbia, Hawaii, Minnesota, Oregon, Rhode Island, or Vermont in 2020 even in a good year for Democrats has a better chance of making a successful a prediction of a crippling snowstorm in Honolulu on Election Day. The real blank spaces are for the Mountain and Deep South and for the Northern Plains, places now very conservative. These places have their limits to offense to sensibilities or to abject failure of a President.
Before I drop polls involving John Kasich, I need to discuss what the binary matchups between Kasich and Clinton really show. It may not be how the 2016 election goes. This is Clinton vs. Kasich under the best possible situation for Kasich in which Kasich wins the nomination easily and is able to win the Presidency with a quiet campaign in which he says nothing controversial and she exposes characteristics that a big chunk of the electorate despises. Nobody has gotten the chance to win an election that way since the 1990s, and this year will be no exception. John Kasich will obviously win the Republican nomination, if at all, after a protracted and exhausting struggle that compels him to say things that will offend people who think Cruz and Trump unacceptable. In the mean time, Democrats have an effective get-out-the-vote drive in the autumn that swings the door shut on some states that look like swing states early but usually go Democratic (like Michigan, Minnesota, New Hampshire, Pennsylvania, and Wisconsin) and pick up some others that went to both George W. Bush and Barack Obama.
I doubt that Kasich wins the election if nominated. If he successfully appeals to Cruz and Trump voters in the primaries he gives Democratic-leaning independents good cause to vote for the Democratic nominee.
So what do the current matchups of Kasich vs. Clinton really mean?
If the Democratic nominee in 2016 becomes a failure as President, then we might see an analogy to 1980 or a partisan inverse of 1932, when the failed President loses to a challenger who makes a largely-positive campaign with care to avoid saying troublesome things except what everyone knows about the troubled incumbent President.
Hillary Clinton vs.
John Kasich 30% -- lead with 40-49% but a margin of 3% or less
40% -- lead with 40-49% but a margin of 4% or more
60% -- lead with 50-54%
70% -- lead with 55-59%
90% -- lead with 60% or more
White -- tie or someone leading with less than 40%.
A landslide in electoral votes like those of 1932 and 1980 is practically impossible because the incumbent President will still win California and New York, which together combine for 84 electoral votes, which is more than Hoover got with six states and 59 electoral votes, let alone the six states and DC that got Jimmy Carter 49 electoral votes. But let me guess what a 44-state landslide for a Republican looks like in 2000 if one concedes four other states and the District of Columbia.