By Moira Warburton
WASHINGTON (Reuters) - Control of the U.S. Senate is at stake in the Nov. 8 midterm elections, as Republicans need to pick up only one seat to win control of the 100-seat chamber, which would allow them to block much of President Joe Biden's agenda.
The chamber is currently split 50-50 between Republicans and Democrats, who are able to control the agenda thanks to Vice President Kamala Harris' tie-breaking vote. Democrats hope to expand their margin.
Here are eight races that could determine the outcome.
Democrat Catherine Cortez Masto, the first Latina to serve in the Senate, is defending her seat against state Attorney General Adam Laxalt, a Republican who spearheaded his party's efforts to overturn Biden's victory there in the 2020 election.
Cortez Masto has been emphasizing abortion rights, while Laxalt has sought to harness voter concerns about rising prices - a pattern playing out in other states as well.
In a state where 30% of the population is Latino, analysts are closely watching whether these voters will continue to drift toward Republicans or whether Democrats can reverse this trend.
Democratic Senator Mark Kelly, a former astronaut and husband of former U.S. Representative Gabby Giffords, is facing Republican Blake Masters, a Republican backed by tech billionaire Peter Thiel. The state is a former Republican stronghold where Democrats have made surprise gains in recent elections - Biden won the state by 0.3% in 2020. Masters has sought to distance himself from controversial comments suggesting Social Security should be privatized. He also recently deleted portions of his campaign website where he advocated for a total abortion ban.
Masters' struggles have led Republicans to pull funding and analysts have shifted their predictions for the race in Kelly's favor.
In what is expected to be a close race, freshman Democratic Senator Raphael Warnock is up against Herschel Walker, who is endorsed by former President Donald Trump.
Walker is a former college football star who has been hampered by a series of scandals, including allegations of domestic violence and allegedly lying about how many children he has fathered.
Warnock, who serves as pastor at the Atlanta church once led by Martin Luther King, Jr., won a surprise victory in a special election in early 2021, giving Democrats control of the U.S. Senate.
Republican Senator Ron Johnson is running against Democrat Mandela Barnes, the state's lieutenant governor. Johnson's false statements about COVID-19 vaccines and Biden's 2020 election victory could make him vulnerable, but he has pulled off surprise victories in past elections.
Republicans argue Barnes is too radical for the state, pointing to his past support for progressive policies like Medicare for All and a 2018 photo in which he is holding a shirt that reads "Abolish ICE," an immigration enforcement agency.
Republican Mehmet Oz, a former brain surgeon and TV host, is competing with John Fetterman, the Democratic lieutenant governor, for Pennsylvania's open seat.
Fetterman has portrayed Oz as elitist and an interloper, criticizing his attempts to connect with the state's working class as ham-handed. In particular, a video released by the Oz campaign where he mispronounced the name of a local grocery chain while shopping for a "crudite" platter garnered criticism online. Oz has also faced accusations of carpetbagging as a longtime New Jersey resident.
Fetterman, by contrast, emphasizes his blue-collar background and campaigns in shorts and a hoodie. He faces questions about his health, as he has made few public appearances in person since suffering a stroke in May.
Republicans nominated Don Bolduc, a retired U.S. Army general who promoted Trump's lie that the 2020 election was stolen, to run against incumbent Democratic Senator Maggie Hassan. Bolduc has attempted to appeal to centrist voters since his primary win, disavowing election fraud claims and saying abortion should be decided by the states. Analysts think Hassan has the advantage, given Bolduc's hard-right statements.
Republican U.S. House Representative Ted Budd faces former state Supreme Court judge Cheri Beasley for an open U.S. Senate seat in a relatively low-key race that has not drawn as much national attention.
Budd, a gun store owner, has emphasized bread-and-butter concerns like inflation to appeal to moderate voters, but he has also backed a national ban on abortions after 15 weeks and has appeared at several rallies with Trump.
Beasley has said she would not be afraid to break with her party to appeal to centrists. North Carolina has been politically competitive for more than a decade, but Republicans have won most statewide contests and analysts give Budd the edge.
Trump-endorsed, Thiel-backed J.D. Vance, author of the hardscrabble memoir "Hillbilly Elegy," should hold the advantage against Democratic U.S. House Representative Tim Ryan in a state that has trended Republican over the past decade.
But Vance's more controversial opinions - that he did not care what happened in Ukraine, claiming the Biden administration was purposely flooding the Midwest with fetanyl - have made the race more competitive than expected.
Ryan has emphasized his blue-collar background and distanced himself from party's liberal wing.
National groups have been pouring in money, and the topic of abortion is front and center since the state's Republican legislature banned all abortions after six weeks.
(Reporting by Moira Warburton in Washington; Editing by Andy Sullivan and Josie Kao)