stump for (one)
To campaign or canvas an area on behalf of a different political candidate, especially by making speeches to large crowds. The former president has been vigorously stumping for his friend and colleague across the Midwest. It will be a huge boost if we can get such a renowned senator stumping for you.
stump for someone
to go about making political speeches in support of someone. The vice president was out stumping for members of Congress who were running this term. Since all the politicians were out stumping for one another, there was no one in the capital to vote on important legislation.