“Martin Van Buren created the Democrat Party in the 1820s for one purpose only-—to protect and perpetuate slavery via the distribution of jobs and “spoils.”
Didn’t Van Buren also help found the anti-slavery Free Soil Party in the 1840s? I know that he ran for President in 1848 on the Free Soil ticket.
Van Buren seems to me like the original Reagan Democrat, meaning a patriotic Democrat whose party shifted so far to the left it left them behind, today's Trump Democrats another example.
In Van Buren's case he was a solid Democrat who slowly became more anti-slavery as Democrats generally became adamantly anti-abolition.
Van Buren did rejoin the Democrat fold in 1852, 1856 and 1860, but in 1861 near the end of his long life, he supported Lincoln against other Northern Democrats (like former President Pierce) who were "neutral" or supportive of Southern secession.
In essence, Van Buren died as a Lincoln Democrat, who valued his country and abolition more than Southern "states rights" to secede.