Based on early cross-party head-to-head polling, there wouldn't have been a Reagan presidency
Whenever articles entitled "A Vote For Trump is a Vote For Hillary Clinton: Why Trump Is A Sure Loser" appear, you know there are going to be problems in the analysis. Such broad generalizations about a popular candidate within his own party will be riddled with holes.
If an analysis on Trump's purported unelectability is based on his "net favorable" ratings compared to other Republicans that are in the race, a weakness is evident. Who has the most favorable "net favorability" ratings among all current candidates? That would be Carson. The same candidate with no primary wins, 8 delegates (Trump has 319 and the lowest "net favorable" rating among all current and former candidates – yet is leading the GOP race), and polling support generally in the single digits around the nation.
Carson also has the highest "favorable" rating (37%) among all current and former candidates. Rubio is second (34%), Trump is third (33%), Cruz is fourth (32%), and Christie (31%) is fifth – although all of these are a statistical tie. The correlation between favorable ratings and performance in the GOP primaries? Zero. It is a useless statistic to date.
The next statistic the anti-Trumpers promote is Trump's poor performance – at present – in head-to-head match-ups against Clinton, and even Sanders (who has no chance of being the Democratic candidate, the job is already Clinton's).
Just a brief browse of historical head-to-head match-ups between possible GOP candidates and the Democratic opponent this early in the primary season raises major red flags if this is supposed to be a criterion to help guide the Republican nomination process.
The 40th president of the United States of America, Ronald Wilson Reagan, is the poster child for why head-to-head cross-party polling at this stage is mostly irrelevant.
Gallup has the polling data for 1980 in the Reagan versus Carter race:
In February and March of 1980, during the earliest stages of the GOP primaries when the establishment candidate George H.W. Bush was still in the race against Reagan, Reagan was being absolutely devastated in head-to-head polling against Carter. Polling data was consistently showing that Carter was trouncing Reagan by 2:1, or about 60% to 30%.
Based on this data, and the current flawed head-to-head cross-party analyses so popular among the anti-Trump faction, Reagan should have been thrown out of the race in favor of Bush. In fact, Reagan remained well behind Carter in head-to-head polling into June.
The GOP nominated the clearly most popular internal candidate (Reagan) anyway, and instantaneously, Reagan closed the gap as he and his team began to focus on the Democratic opponent.
What ultimately happened was that Reagan won the 1980 general election by taking 44 states, beating an incumbent president by a full 10% of the popular vote, and taking 91% of the electoral college. In 1984, Reagan expanded his electoral domination and provided the two largest back-to-back presidential victories in American history.
But had GOP pundits been basing the preferred choice of party nominee in late February/early March of 1980 not on support within the party itself, but rather on hypothetical head-to-head match-ups with the Democratic opponent, Reagan would never have been the nominee – and there never would have been a President Reagan.
Other notable fails include Gore versus Bush in 2000, when early primary polling showed Gore losing by a significant margin to Bush in hypothetical polls, but where Gore actually won the popular vote come election time. Kerry was winning the head-to-head match-ups against Bush in March 2004 by 6%, but lost the general election by several percent. McCain was ahead of Obama in much of the very early head-to-head polling during 2008, but lost by 7% in a landslide win by Obama.
In April 1992, Clinton was consistently behind Bush by 20% in head-to-head match-ups, staying well behind Bush up until May/June, but ultimately won a landslide victory in the general election.
Head-to-head match-up polling across parties is relevant and reliable only after the conventions. Before then, it is a game of chance that only fools take seriously.