on his return to massachusetts, banks immediately ran for congress, for a seat vacated by the resignation of radical republican daniel w. gooch. the massachusetts republican party, dominated by radicals, opposed his run, but he prevailed easily at the state convention and in the general election, partially by wooing radical voters by proclaiming support for negro suffrage. he served from 1865 to 1873, during which time he chaired the foreign affairs committee. despite his nominally moderate politics, he was forced to vote with the radicals on many issues, to avoid being seen as a supporter of president johnson's policies. he was active in supporting the reconstruction work he had done in louisiana, trying to get its congressional delegation seated in 1865. he was opposed in this by a powerful faction in louisiana, who argued he had essentially set up a puppet regime. he also alienated radical republicans by accepting a bill on the matter that omitted a requirement that states not be readmitted until they had given their african-american citizenry voting rights. despite his position as chair of an important committee, banks was snubbed by president grant, who worked around him whenever possible.