But he had coupled his opposition with a declaration of his own unalterable opposition to that extension, and had said, speaking of those who were in favor of the declaration: "It is not their thunder." He declared in the Senate, as late as 1848: "My opposition to the increase of slavery in the country, or to the increase of slave representation in Congress, is general and universal.
It has no reference to lines of latitude or points of the compass.

I shall oppose all such extension, and all such increase, at all times, under all circumstances, even against all inducements, against all combinations, against all compromises." So the Anti-Slavery Whigs eagerly supported him as their candidate for the Whig nomination in 1848.
If Mr.Webster had been nominated for the Presidency in 1848, the Free Soil Party would not have come into existence that year.

There would have been probably some increase in the numbers of the Liberty Party; yet the Anti-Slavery Whigs of Massachusetts would have trusted him.

But the nomination of General Taylor, a Southerner, one of the largest slaveholders in the country, whose laurels had been gained in the odious Mexican War, upon a platform silent upon the engrossing subject of the extension of slavery, could not be borne.

The temper of the Whig National Convention was exhibited in a way to irritate the lovers of freedom in Massachusetts.