WASHINGTON — Senate Majority Leader Mitch McConnell will lay out his case to move on from investigations into President Donald Trump and his 2016 campaign, calling the matter “case closed” even as Democrats intensify their probes into Trump’s conduct. McConnell, R-Kentucky, who faces re-election next year, argues that Democrats are continuing to relitigate an election result that is now more than 2 years old, and plans to make a detailed argument in a floor speech Tuesday morning to declare the matter finished and instead focus on legislation. “With an exhaustive investigation complete, would the country finally unify to confront the real challenges before us?” McConnell plans to say later Tuesday, according to excerpts provided by his office.