Sanders and Clinton supporters have been arguing for months over which candidate would do better in the general election. This is not an academic question by any means. Given the abhorrent Republican frontrunner and his equally despicable leading challengers, the prevailing sentiment on the left is the Republican must be stopped. If either Bernie or Hillary could be shown to be significantly stronger in November, that candidate would have a strong claim on Democratic primary voters.

The arguments for Bernie

As a Bernie enthusiast, I have inclined to the belief Bernie would do better against any of the GOP leaders.  I so argued here in the afterglow of Bernie's impressive early win in New Hampshire.  A few days later, I posted an image of CNN national polls showing Sanders would beat all five of the then viable Republicans relatively handily while Clinton would lose to all except Trump whom she would defeat by 1 point.

March 1 CNN polls tell essentially the same story.  Sanders beats Trump and Cruz by double-digits and Rubio by 8 points.  Clinton loses to Crubio but does defeat Trump by a comfortable 8 points.

The argument that Sanders is a better general election candidate does not rest solely on polls.  Sanders has shown strength among the young and white working class voters.  These are two demographics that Democrats have struggled to attract in recent years.

The former have often stayed home with the latter gravitating to Republican candidates.  The danger of nominating Clinton, Bernie backers contend, is some of these capricious voters may not back Clinton enthusiastically, others may not vote at all, and worst of all, some of Bernie's white working-class voters may turn to Trump.  By contrast, Clinton's base includes African-Americans, older women, and liberal professionals.  Given the loyalty such voters have shown in recent years to Democratic Presidential candidates, it seems logical a large majority of them will stay in the Democratic fold even if their first choice loses the nomination to Bernie Sanders.

Yet another argument you hear from Bernie proponents is he does better on terrain the two major parties contest.  So far, this seems to be the case.  There have already been a number of contests in so-called swing states and Sanders has done well in them.

The candidates essentially tied in Iowa, Sanders won big in New Hampshire.  He came close in Nevada, lost big in Virginia, and won the Colorado caucuses.  Clinton's big wins, with the exception of Virginia, have come in dark red states.  She did eke out a victory in Massachusetts but if Massachusetts is competitive in November, there will be - shudder - a President Trump or possibly - shudder shudder - Cruz next year.

Finally Sanders possesses a significant advantage in enthusiasm.  His rallies have generated much bigger crowds than any other candidate's except for Donald Trump's.  His campaign has generated many more individual contributors than any other in American history.

So Sanders can plausibly claim a larger potential pool of voters than Clinton, that polls consistently show him to be more formidable against the Republicans, he is stronger in swing states, and that he has generated more excitement.

The arguments for Hillary

Clinton adherents have their own arguments and responses.  Their primary contention is the polls overstate Bernie's support since he has never faced an onslaught from the Republican right-wing media machine.  Whereas Hillary has been one of their favorite pinatas for twenty-five years.  If Sanders were to get the Democratic nomination, her advocates insist, ceaseless attacks on him as a leftist fool, an atheist, a socialist, and a consorter with Communist dictators would quickly take the bloom off his rose among independents and working-class voters.

Clinton's team adduces additional arguments in her favor.  Karl Rove's super-Pac Crossroads ran ads before the Iowa caucuses attacking Hillary.  The Clinton team contends this proves Republican fear Clinton more than Sanders and therefore are trying to defeat her before the general election.

The Clinton cohort also notes that Sanders may have big audiences at his rallies but he has failed to turn out record numbers of voters either for him or in the primaries.  For his revolution to occur, he will need to bring millions of new voters to the polls, yet the turnout in the Democratic primaries so far has been down significantly since 2008.

Finally, Clinton's fans insist that if she really needs enthusiasm, she'll get it from the Republican nominee.  Trump is so frightening due to his fascistic style of campaigning, racism, misogyny, and lack of any experience that Democrats will turn out in droves to vote against him.  Cruz is equally anathema or will be when the nation at large becomes conversant with his record say Hillary's helpers.

Analysis

Both sides make some good arguments and also pull out a few rocks.  The polls showing Sanders as the stronger Democrat may be of little value but they are not useless.  They tell us with some degree of accuracy where the electorate is right now.  They also receive support from the diametrically opposed favorability ratings of the two candidates.  Currently, the HuffPost Pollster has Clinton's net favorability at -14.  Bernie Sanders has a +13 favorability rating.

While it is true that Sanders hasn't been vetted for nearly as long or as aggressively by political enemies as Hillary Clinton has, it is not true that he is a political unknown.  By this time, most Americans have a sense of who he is.  Attacks on him as a socialist or radical far outside the mainstream of political sensibilities may have some effect but they will not be on a relative unknown.

Moreover, just because Clinton has been hit hard in the past doesn't mean new attacks won't hurt her.  Her email setup at the State Department did violate federal rules yet Sanders has shied away from raising it against her.  The Republicans will not be so accommodating.  If Trump is the nominee, he can plausibly claim she is the candidate of Wall Street more than he is since he doesn't take corporate (or any) contributions and didn't set up a super-Pac.

The fact that Karl Rove ran ads against Clinton would be strong evidence that she would be a tougher out in November if Karl Rove were the mastermind some perceive him to be.  But his embarrassing performance during election night 2012 should put to rest any notion that he is an infallible political guru.  In any case, Rove's decision to put a thumb on the scale for Bernie doesn't prove he thinks Clinton would be a more formidable opponent.  It may merely reflect the view that a drawn-out primary campaign would weaken her in advance of the general election.

Clinton's acolytes are on stronger ground when they question whether Sanders really would benefit from more excited supporters.  After all, rabid young voters didn't put him over the top in what now appear to have been the must-win states of Iowa and Nevada.  Likewise, Sanders couldn't prevail in Massachusetts with a mostly white populace and a dozen or so renowned colleges and universities.

On the other hand, the contention that the Republican candidate will rev up Clinton's base hardly seems to militate in her favor.  Any fears of a Trump or Crubio candidacy would likely excite Clinton's supporters to vote for Sanders if he's the Democratic nominee as much as it would motivate his primary supporters to vote for her in the general election if she is nominated in Philly.

Conclusion

If the popular vote determined the general election, I would feel comfortable saying Sanders would be stronger than Clinton.  He can compete for white working class voters and should be able to consolidate Clinton's traditional Democratic coalition behind him.  He is far less unpopular and is perceived as much more trustworthy.

But we don't simply count up all the votes in the United States.  We assign electors based on which candidate prevails in each state.  On this score, despite arguments to the contrary, I think Clinton may have the advantage.  The largest swing state by far is Florida.  Clinton's base of African-Americans and older voters comprise a big percentage of eligible voters in the Sunshine State and might well decide Florida in her favor.

Although Texas has been reliably conservative, it is starting to show faint tinges of blue.  Clinton's popularity there on super Tuesday suggests that she might be able to force the Republican candidate to divert time and money to the Lone Star State.  Clinton enjoys a comfortable lead over Sanders in critical Ohio and also Michigan.  She also probably would do better in North Carolina which Barack Obama won in 2008.

It is plausible Sanders, but not Clinton, could win Colorado, West Virginia, New Hampshire, and possibly Wisconsin.  But these states, important as they are, pale in size compared to the states where she has a comparative advantage.

Given the vagaries of the electoral college, Clinton may well be as strong as or even stronger than Sanders in the general election even if he could garner more votes nationally.  It is therefore impossible to state with any degree of confidence at this point which Democrat has a better chance of winning the general election.