The 2008 Republican presidential ticket is split between the two GOP candidates in the hotly contested Senate race.In a 60-second radio spot released Friday, U.S. Sen. John McCain, R-Az., supports fellow Sen. Richard Lugard, R-In., and reminded voters the six-term lawmaker has stood against President Obama's administration. The former presidential candidate also addressed criticisms levied by state Treasurer Richard Mourdock, adding that Lugar is not the president's favorite Republican."Dick Lugar has always put his country first, helping keep our nation safe and secure as the foremost expert on national security in the Unites States Senate," says McCain. "Yet, some in Indiana are claiming Dick Lugar is Obama's friend. That's ridiculous. And I know it firsthand. Because I fight alongside him every day in the Senate. Dick Lugar is a patriot and a hero, and we need him in the United States Senate.Listen here.With less than two weeks until Election Day, the Mourdock campaign has chosen to tout a key endorsement that underscores the GOP challengers Tea Party credentials. In statement, former Alaska Governor Sarah Palin backs Mourdock, adding Lugar's 35-year-tenure must come to an end."Indiana deserves a conservative in the Senate who will fight for the Hoosier State, uphold our Constitution, and not just go along to get along with the vested interests of the permanent political class in D.C.," says Pailin. "Richard Mourdock is the conservative choice for Indiana. Senator Lugar’s 36 years of service as a Senator are appreciated, but it’s time for the torch to pass to conservative leadership in Washington that promises to rein in government spending now."Indiana Republicans head to the polls on May 8.