LOUISVILLE, Ky. — Maybe no one was more invested in Tuesday’s election than Sen. Mitch McConnell, R-Kentucky..

The minority leader for the past eight years, McConnell on Tuesday was on the cusp of fulfilling his life’s ambition to be the majority leader of the Senate.

His journey to this moment began when he was a Senate intern in the early 1960s. His approach has been focused and methodical, each step thought out, every hardship endured with an eye toward what was around the next corner.

In Washington and here on the trail in Kentucky, McConnell, 72, has promised to run the Senate with more freedom for rank-and-file senators than has Majority Leader Harry Reid, D-Nev.

“The Senate has done nothing essentially for the last four years,” McConnell said recently on the campaign trail. “The Senate’s going back to work, and our first goal will be to see if there are things we can agree on with the president.”

McConnell is a creature of the Senate, adept at using its arcane parliamentary rules to his political advantage. He knows how to tie the Senate in knots to deny the other side a victory, and Democrats, particularly Reid, contend that he has abused that power over the past eight years with a record-setting number of filibusters.

But McConnell also has a substantive track record as a deal-maker, working closely with Vice President Joe Biden. While he has no personal relationship with Obama, as majority leader, McConnell would be the natural GOP point man in any such talks during the president’s final two years in office.

Over the years, McConnell has developed a public persona as stoic and unemotional, but he has an almost unique ability to provoke heated reactions from his adversaries. Kentucky Democrats, who have never been able to beat him in an election, despise him for the scorched-earth campaigns he has so successfully run against them for more than 30 years.

Democrats in Washington revile him as a partisan obstructionist, the architect of a political strategy that they compare to setting fire to a village and then claiming credit for riding in on the firetrucks to save it.

On Saturday at Transylvania University, where McConnell’s hero Henry Clay once taught law, Democrats mocked the senator’s claims of wanting to restore the Capitol’s grand traditions. “It’s the same Washington, D.C., he spent the previous six years breaking,” Todd Hollenbach, the state treasurer, said at a rally for McConnell’s challenger, Alison Grimes.