Sen. Tallian has been an outspoken critic of Gov. Mike Pence and is the second Democrat to officially enter the race.
The Democratic candidate and former Indiana House Speaker, who also ran in 2012, announced the news Thursday.
John Gregg said in February that he was considering a possible 2016 run for Indiana governor.
Indiana's Religious Freedom Restoration Act has become the subject of fierce debate across the nation.
Researchers say microbeads are dangerous to the environment and can potentially lead to health problems for people that use products that contain them.
The bill aims to speed up the rescue of child victims of human trafficking.
After conflicting federal rulings on healthcare subsidies, Gov. Mike Pence hopes Congress will rethink healthcare reform.
Evan Bayh says he is not ruling out a run for governor of Indiana in 2016.
U.S. Attorney Joe Hogsett is resigning at the end of the month, again sparking speculation that he might run for a statewide office.
Governor Mike Pence's proposed Healthy Indiana Plan has been met with both support and criticism in Indiana.