On the stump means to take part in political campaigning. The idiom on the stump comes from the habit of early American politicians traveling the countryside to make campaign speeches. In rural areas there was often no stage or place for a speaker to rise high enough to be seen and heard by a crowd, so the politician would stand on a tree stump. In time, traveling around the countryside in order to campaign for office came to be referred to as being on the stump.
A stump speech is the speech a candidate makes while he’s on the stump. Generally, a candidate makes the same speech over and over to different audiences.
Mr. Sanders has long been a target of gentle ridicule from Mr. Cruz on the stump, though his most pointed vitriol is almost always reserved for President Obama and Hillary Clinton. (The New York Times)
No matter how much one may support Mr. Sanders’ vision of what America can or should be, there are a few stubborn facts that demonstrate how the candidate has no hope of achieving virtually any of the promises he’s making on the stump. (The Observer)
That’s how some in the media have portrayed the relationship between Trump and Adele after news broke this week that Trump has played the British pop star’s music on the stump without her thumbs-up. (The Columbia Journalism Review)
he only positive thing to come out of Sarah Palin’s mystifying and surreal Trump stump speech earlier this week: Tina Fey came back to Saturday Night Live solely to mock it. (Vanity Fair Magazine)
For Trump, the lack of a script has not prevented a clearly recognizable stump speech from emerging. (TIME)