On July 31, 1844, Rhett launched the Bluffton Movement, which called for South Carolina to return to nullification or else declare secession.

It was soon repudiated by more moderate South Carolina Democrats, including even Senator John C. Calhoun, who feared it would endanger the presidential candidacy of James K. Polk.

After the Nashville Convention, Rhett, William Lowndes Yancey, and a few others met in Macon, Georgia on August 21, 1850, and formed the short-lived Southern National Party.

He continued to express his fiery secessionist sentiments through the Charleston Mercury, now edited by his son, Robert Barnwell Rhett Jr.

The 1860 Democratic National Convention met in Charleston, South Carolina and a large bloc of Southern delegates walked out when the platform was insufficiently pro-slavery.

That led to the division of the party and separate Northern and Southern nominees for president, which practically guaranteed the election of an anti-slavery Republican, which in turn triggered declarations of secession in seven states.

During the 1860 presidential campaign, a widely credited report in the Nashville Patriot said that the outcome was the intended result of a conspiracy by Rhett, Yancey, and William Porcher Miles hatched at the Southern Convention in Montgomery, Alabama in May 1858.

It will be difficult, even for many of our own people, to believe that so glorious a cause as the one we fought for should have been sacrificed by the prejudices & want of judgment & foresight of one man [Jefferson Davis]!