Samuel returned to the House of Commons following the 1929 general election. Two years later, he became deputy leader of the Liberal Party and acted as leader in the summer of 1931 when Lloyd George was ill. Under Samuel, the party served in the first National Government of Prime Minister Ramsay MacDonald formed in August 1931, with Samuel himself serving as Home Secretary. However the government's willingness to consider the introduction of protectionist tariffs and call a general election to seek a mandate led to the Liberal Party fragmenting into three distinct groups. Sir John Simon had already led a breakaway group of MPs to form the Liberal National Party.