Kentucky Secretary of State Alison Lundergan Grimes threatened to block Sen. Rand Paul by taking him to court if he decides to run for both Senate and president in 2016.

Paul, a heavy favorite to win a second Senate term if he's allowed to stay on the ballot, announced in early December that he would run for Senate again in 2016, Bloomberg reported. He will also decide on a presidential run in "the March/April time frame."

But challenging Paul, the Democratic Senate nominee not only declared that she will not be "bullied," but also that she won't allow him to run simultaneously for president and reelection to the Senate in 2016.

"The law is clear," Grimes told WHAS-TV, an ABC affiliate in Louisville. "You can't be on the ballot twice for two offices."

Currently, Kentucky's law states that "no candidate's name shall appear on any voting machine or absentee ballot more than once," except for certain special elections, according to the Associated Press.

"I will not be bullied," Grimes, who would be a top Democratic recruit to run for Senate in 2016 if Paul bows out, said. "I think hopefully the people of Kentucky understand that over the course of this past year, and I will not hesitate to seek help and assistance in the opinion of a court."

However, the 36-year-old has not decided whether she will be seeking a second term as secretary of state in the 2015 election, she told the Louisville ABC affiliate on Wednesday. "If she doesn't run for reelection as the state's chief election official, she would have no legal basis to challenge Paul's dual candidacy," Politico reported.

"There's encouragement from all different directions, no shortage of opinions, that's for sure," she told the station. "But no election should be run unless it's in your heart and the facts are there to win, and that's what I will weigh before I make any determination."

According to an August poll by SurveyUSA, a majority of people in Kentucky opposed changing the law that would allow Paul to run for both offices, The Washington Times reported.

It would be a "tough challenge" for Paul to run for both offices in 2016, Senate Minority Leader Mitch McConnell (R-Ky.) said.

"It is one of the things Senator Paul has to grapple with in trying to figure out what the way forward is," McConnell said at a recent event hosted by Politico.

Meanwhile, a Paul spokesman did not have an immediate response to Grimes' legal threat.