BOSTON — When the Tea Party Express pulls into the city where the conservative movement got its name, the crowd will be as notable for who’s not there as for who is.

Sarah Palin is the keynote speaker Wednesday, but Republican Sen. Scott Brown is skipping the event. The movement claims his upset January election as its proudest moment.

Brown says he’s too busy with his congressional duties, but Tufts University political science professor Jeffrey Berry says he believes the senator is worried about being associated with the movement’s more radical elements.

Republican gubernatorial candidate Charles Baker is also skipping the rally, saying he has a prior commitment 40 miles away in Worcester, the state’s second-largest city.

Tea party rallies were being held Tuesday in Missouri, Nebraska and New York.

FILE – In this Dec. 20, 2009 file photo, former Arkansas Gov. Mike Huckabee speaks in Omaha, Neb. Huckabee, a possible Republican presidential candidate in 2012, says the effort to allow gays and lesbians to marry is comparable to legalizing incest, polygamy and drug use. Photo by THE ASSOCIATED PRESS

DAVE WEAVER