Suppose the Whigs had gotten their way after Harrison's death and Congress forced a special election to be held to complete the remainder of Harrison's term. Who would be nominated by each party, and how would the subsequent election go?
I suspect that despite his loss, Van Buren would be best positioned to be the Democratic nominee again. He was the frontrunner in 1844 until Texas became an issue, so unless acting President Tyler somehow expedited the annexation process to help him win a full term, I do not see how Van Buren would lose the nomination. Given Whig dissatisfaction with Tyler, they would probably go with Clay. Tyler may have run an independent candidacy, as he originally did in 1844, and without an expansionist Democratic candidate likely would have stayed in the race.
As for the general election, Van Buren would probably have done slightly better in the North by virtue of running against weaker opponents. However, much of his Southern support would be lost to Tyler. Thus, I think a map similar to this would be the likely outcome (party loyalty may have given Van Buren Arkansas and Alabama, although I am skeptical):
In which case Clay probably would have won the vote in the House of Representatives. Thoughts?