Candidates in a U.S. Senate special election in Mississippi are promoting endorsements they’re receiving from other politicians.

Republican Sen. Cindy Hyde-Smith is backed by President Donald Trump, and they are scheduled to appear together at a rally Tuesday in northern Mississippi’s DeSoto County.

Democratic challenger Mike Espy is endorsed by Sen. Cory Booker of New Jersey and former Massachusetts Gov. Deval Patrick, who have both traveled to Mississippi for him.

Republican challenger Chris McDaniel is endorsed by former U.S. Rep. Ron Paul of Texas, who issued a news release last week. Paul was the Libertarian nominee for president in 1988 and a Republican candidate for president in 2008 and 2012.

A University of Mississippi political science professor, Marvin King, says most endorsements are unlikely to sway an election.

“There are just too many factors at play to say that endorsements are going to be decisive, but there’s no doubt that some people look at them,” King told The Associated Press on Friday. “They put endorsements in the basket of all things they look at when deciding on a candidate — perception of a candidate, a candidate’s policies. … Endorsements kind of go into that blender.”

The winner of the special election will serve the final two years of a six-year term started by longtime Republican Sen. Thad Cochran, who retired in April.

Republican Gov. Phil Bryant appointed Hyde-Smith, who was state agriculture commissioner, to temporarily succeed Cochran. She’s now facing Espy and McDaniel, as well as Democrat Tobey Bernard Bartee, a former military intelligence officer who is spending little to campaign.

Party labels will not appear on the ballot for this race, but candidates are telling voters their political affiliation. If nobody receives a majority on Nov. 6, the top two advance to a Nov. 27 runoff. The race could have national significance if the partisan balance of the Senate is still undecided.

Hyde-Smith received the coveted Trump endorsement on Aug. 23, when he wrote on Twitter: “Cindy has voted for our Agenda in the Senate 100% of the time and has my complete and total Endorsement. We need Cindy to win in Mississippi!”

In 1986, Espy became the first African-American to win a U.S. House seat in Mississippi since Reconstruction, and in 1993 he became President Bill Clinton’s first agriculture secretary. Mississippi has a 38 percent black population, and Espy needs strong turnout among black voters who traditionally vote for Democrats. He is also campaigning as someone who will work across lines of race and party.

Booker and Patrick are African-American, and each was elected to a statewide office with support that crossed lines of race. Booker is a former Newark mayor and won a Senate seat in 2013. Patrick was Massachusetts governor from 2007 to 2015. When Espy was in the Clinton Cabinet, Patrick was the assistant U.S. attorney general for civil rights.

“I’m a Democrat, but not the sort of Democrat who believes you need to hate Republicans to be a good Democrat,” Patrick said Sept. 22 at an Espy event, as Espy nodded. “I think the people of Mississippi and the people of America need problem solvers in Washington — people who understand that not any one party has a corner on all the best ideas.”

McDaniel, a third-term state senator, has been a tea party favorite and received financial support from libertarian-leaning groups when he nearly unseated Cochran in the 2014 Republican primary. Paul also endorsed him then.

“Our country desperately needs courageous leaders to stand up to the establishment in Washington,” Paul said in his recent statement for McDaniel. “Mississippi and the rest of the country need Chris McDaniel in D.C.”

King, the political scientist, said presidential endorsements have the most influence because people know who a president is.

“How many Mississippians know who Deval Patrick is? Or even Cory Booker? Or even Ron Paul?” King said. “It’s all relative.”

Emily Wagster Pettus has covered Mississippi government and politics since 1994. Follow her on Twitter at EWagsterPettus.