Stephen Kenny’s side, who take on Dutch side AZ Alkmaar on Thursday, dominated throughout as goals in either half from Patrick McEleney and Daryl Horgan put the Donegal men to the sword.
The result means their lead over second placed Cork City is in double digits, albeit with two matches more played. In a game that was largely one-way traffic, the visitors had goalkeeper Ciaran Gallagher to thank for keeping the scoreline down.
He was called into action as early as the third minute when he was forced to finger tip John Mountney’s cross over the crossbar after it took a deflection off Ciaran Coll.
Gallagher could do nothing about Dundalk’s opener on six minutes, with McEleney picking the ball up 30 yards from goal before driving at the Harps defence to fire a low shot to the bottom corner.
The pressure continued after that with Gallagher turning shots from both Mountney and Horgan around the post before Paddy Barrett hit the crossbar with a header before the break.
A serious looking injury to Harps striker Ruairi Keating that saw him stretchered off marred the start of the second half with manager Ollie Horgan sent to the stands in the 69th minute for complaining about a booking for Gallagher. The visitors did have one chance to level when Keith Cowan got on the end of a free midway through the half but it was comfortable for Gary Rogers.
Dundalk then finally put the game to bed on 75 minutes. Good work by substitute Ronan Finn on the right saw him pick out Horgan at the near post, with the winger steadying himself before rifling high to the roof of the net to secure the win.
Rogers; Gannon, Barrett, Boyle, Massey; Mountney (Finn 68), Benson, Shields, Horgan; McEleney (Shiels 77); McMillan (Kilduff 82).
Gartland, O’Donnell, Grimes, Sava.
Gallagher; J Mailey, P Mailey, Cowan, McMonagle, C Coll; Funston (Banda 85), Harkin, McNamee (Coyle 76), Curran; Keating (Scully 52).
N Doyle (Dublin).