(CNN) - Polls are open in Tennessee, where a Republican gubernatorial battle and some contentious House nomination fights are in the spotlight in Thursday's primary.
Five candidates are on the ballot in the GOP contest for governor, but recent polls indicate it's a three-man race between Knoxville Mayor Bill Haslam, Rep. Zach Wamp and Lt. Gov. Ron Ramsey. The race grabbed national attention last month because of controversial comments by two of the candidates.
Last month Wamp appeared to suggest that Tennessee should consider secession in light of mandates forced on the states by the Obama administration's health care bill. The eight-term congressman later walked back from those comments.
Ramsey also drew attention to himself last month after he was seen in a You Tube video questioning whether Islam is a religion while expressing his opposition to the expansion of a mosque in Murfreesboro, Tennessee, which has become a hot-button issue in the city about 35 miles southeast of Nashville.
Ramsey, who has been endorsed by 20 Tea Party organizations, said he is a supporter of religious freedoms but such protections may not extend to facilitating "shariah [Islamic] law into the state of Tennessee… into the United States.
"Now, you could even argue whether being a Muslim is actually a religion, or is it a nationality, way of life, a cult, whatever you want to call it," he continued. "But certainly we do protect our religions, but at the same time, this is something we are going to have to face."
Following criticism, Ramsey defended his comments, saying, "My concern is that far too much of Islam has come to resemble a violent political philosophy more than peace-loving religion."
"Haslam has led the race from the beginning and comes into today with the advantage," says Nathan Gonzales, political editor of the non-partisan Rothenberg Political Report. "Wamp and Ramsey have struggled to put together even money to broaden their geographic bases and knock the other guy out to become the clear alternative to Haslam."
The winner of the GOP primary will face off in November against Mike McWherter, a Democratic businessman and son of a former governor. The race is to succeed two-term Democratic governor Phil Bredesen, who is prevented by term limits from running again. Political handicappers think Republicans have a good shot at winning back the governor's office.
Also grabbing attention are competitive primaries on both sides for the open seats in Tennessee's 3rd, 6th and 8th congressional districts.
The Center for Responsible Politics calls the race in 8th District the most expensive House contest in the country. The Memphis Commercial Appeal reports that $5.2 million has already been spent in the battle to fill the seat of retiring 11-term Democratic Rep. John Tanner. The Republican establishment's choice for the nomination, Stephen Fincher, a farmer and gospel singer, is being challenged by two physicians.
In the 6th District, five Democrats and seven Republicans are vying to replace retiring 13-term Democratic Rep. Bart Gordon. In both the 6th and 8th, the GOP primaries have turned negative.
In the third district, 11 GOP candidates and four Democrats are hoping to succeed Wamp.
Race is a crucial issue in the Democratic primary for the 9th District, which covers Memphis and has a large African-American population. Two-term Democratic Rep. Steven Cohen is facing a primary challenge from former Memphis Mayor Willie Herenton, who is black.
Herenton has been urging voters to elect him as the only African-American member of the state's Congressional delegation, saying, "It is as if only white people live in the great state of Tennessee. No African-Americans. I believe that it is very clear to the majority of the citizens of this community that we lack representation."
Cohen ,who served as a state lawmaker in the area before being elected to Congress, has campaigned on what he's done for education and health care in the area. He said, "I represent everybody and I work hard for people to get them opportunities. And I just think that race should not be an issue in 2010."
President Obama and the Congressional Black Caucus back Cohen.