The secular view, written at the time, is that Smith died because the Mormons were not politically monolithic.
In all fairness, they were caught between two political factions, and both demanded the Mormon vote, “or else”. So after due consideration, Smith promised one of the factions the Mormon vote. And though encouraged to vote that way, enough Mormons voted for the other side that it split their vote, and created two political enemies.
While there was a lot more involved before things went to heck, that certainly got the ball rolling.
It should be noted that even today, while the majority of Mormons tend to vote conservative Republican, there is a minority that pretty much fill the spectrum of the political left, from liberal to barking Moonbat.
I understand that people say mormons vote conservative, you would have to show me when and were this actually happens.
#1...At one point in the early 1840s, Smith's Nauvoo, IL built-up Mormon community was at large -- or larger -- than Chicago was at the time.
#2...In 1844, Smith himself had declared himself a candidate for POTUS...something he wouldn't have done if he was dealing with political rivalry in Nauvoo...which he really didn't have.
And we've seen them all on FR!