Senate Majority Leader Harry ReidHarry Mason ReidDems search for winning playbook Dems face hard choice for State of the Union response The Memo: Immigration battle tests activists’ muscle MORE (D-Nev.) is hosting a fundraiser for Alison Lundergan Grimes, Senate Minority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellSessions: 'We should be like Canada' in how we take in immigrants NSA spying program overcomes key Senate hurdle Overnight Finance: Lawmakers see shutdown odds rising | Trump calls for looser rules for bank loans | Consumer bureau moves to revise payday lending rule | Trump warns China on trade deficit MORE's (R-Ky.) Democratic opponent.

The move marks a shift for Reid, who late last year said he wouldn't campaign against McConnell because he didn't think it was "appropriate." 

Though McConnell pledged not to campaign against Reid during his 2010 race, he also shifted course and helped Reid's GOP opponent, Sharron Angle, raise money.

In 2004, GOP Senate Leader Bill Frist (R-Tenn.) campaigned for John ThuneJohn Randolph ThuneWeek ahead: Tech giants to testify on extremist content Overnight Tech: GOP senator presses Apple over phone slowdowns | YouTube cancels projects with Logan Paul after suicide video | CEOs push for DACA fix | Bill would punish credit agencies for breaches GOP senator presses Apple on phone slowdowns MORE (R-S.D.) against then-Democratic Leader Tom Daschle (D-S.D.).

The fundraiser, first reported by Kentucky news outlet Channel 2, is scheduled for Oct. 11 at a McCormick & Schmick's restaurant in Las Vegas, and is organized by the Searchlight Leadership Fund, an organization Reid founded.

Tickets range from $1,000 for an individual to $5,000 for a political action committee co-host.

The Kentucky Republican Party pounced on the fundraiser. Spokeswoman Kelsey Cooper drew ties between the candidate and Reid's positions on coal.

"It should tell Kentuckians all they need to know that the biggest supporter of Alison Lundergan Grimes' campaign is Harry Reid, the man who thinks 'coal makes us sick.' If Alison was elected to the Senate, it would ensure that liberal Harry Reid and Barack ObamaBarack Hussein ObamaMcCarthy: ‘No deadline on DACA’ Democrats will need to explain if they shut government down over illegal immigration Trump’s first year in office was the year of the woman MORE continue to set national coal policy rather than a Kentucky champion for coal, Mitch McConnell," Cooper said in a statement.

Coal mining is a big industry in Kentucky, and Republicans believe Lundergan Grimes may be vulnerable because of Democratic-backed policies to curb emissions from coal-fired power plants, which opponents say will hurt the coal industry.

The Lundergan Grimes campaign and Reid's office didn't respond to requests for comment.