By Tim Ghianni

(Reuters) - U.S. Senate minority leader Mitch McConnell, a Kentucky Republican, will face a 2014 election challenge from popular Democratic Secretary of State Alison Lundergan Grimes.

At a press conference on Monday in Frankfort, the state capital, Grimes announced her candidacy and said McConnell, who has represented the state in the Senate for 28 years, has been obstructionist in Washington and is out of touch with average citizens.

A poll in late May by the Democratic firm Public Policy Polling found McConnell and Grimes tied at 45 percent each. The poll also showed McConnell with a 44 percent approval and 47 percent disapproval rating.

The National Republican Senatorial Committee immediately attacked Grimes, issuing a statement after her announcement saying that Grimes would oppose the coal industry, a fixture of the Kentucky economy for decades.

"Just last year, Alison Lundergan Grimes stood proudly at the Democratic National Convention to nominate Barack Obama, who has followed through on his promise to destroy the coal industry; in essence declared a war on the state of Kentucky and the middle class families who call it home," the statement said.

Obama lost Kentucky in the presidential election last year, but the state has a history of electing moderate Democrats to statewide office. In addition to Grimes, the state has a Democratic governor. The state's other U.S. senator is Rand Paul, a conservative Republican.

McConnell was elected Republican leader in 2006. He first won election to the U.S. Senate in 1984, defeating a long-time incumbent to become the first Republican to win a statewide Kentucky race since 1968.

(Reporting by Tim Ghianni; Writing by Greg McCune; Editing by Steve Orlofsky)