Seeking to ensure that Van Buren would replace Calhoun as his running mate, Jackson had arranged for a national convention of his supporters. The May 1832 Democratic National Convention subsequently nominated Van Buren to serve as the party's vice presidential nominee. Van Buren won the nomination over Philip Pendleton Barbour (Calhoun's favored candidate) and Richard Mentor Johnson due to the support of Jackson and the strength of the Albany Regency. Upon Van Buren's return from Europe in July 1832, he became involved in the Bank War, a struggle over the renewal of the charter of the Second Bank of the United States.