PORTRUSH, Northern Ireland, June 30, 2012 (AFP) - Irishman Harrington shot a third-round level-par 72 to remain in a share of third place at 10 under par, still two strokes off the lead heading into Sunday's final round.
Welshman Jamie Donaldson, looking to secure a first European Tour success in over 250 events, carded a 69 in rainy and windy conditions to move to 12 under par, one stroke clear of England's Anthony Wall (67).
Donaldson, 36, began with a bogey but immediately recovered with a superb eagle at the second hole.
"The eagle on two was pretty close to a 'two', but it's just nice to be back in the frame," he said.
"I have been knocking on the door a few times for that first win so we've just got to keep playing the same way as I did today." 
Harrington had suggested at the close of day two he would rather be chasing and putting pressure on those in front, and when this was brought to Donaldson's notice, the former Welsh Amateur champion responded:
"The only person I'm really playing against is myself so I have got to stay out of my own way and let the shots take care of themselves."
Wall, 37, captured his only Tour title in winning the 2000 Alfred Dunhill Championship in South Africa and since then has managed just five second-place finishes.
The Surrey golfer declared his round, featuring six birdies and just one bogey, to be the best of his career to date.
"I would have to say that round today is close to the best I've ever had," he said.
"I shot 67 in the 2006 British Open at Hoylake, but given the conditions today that was easily my best."
Wall is spending the week sharing the £600 ($942) cost of sharing a nearby caravan with fellow English golfer Andrew Marshall, but if he captures a second Tour title he will earn a first prize cheque for 333,330 euros ($422,000).
Harrington, who is looking to end a four-year drought without a win since capturing the 2008 PGA Championship, admitted he knows little of Donaldson or Wall.
"I'm not exactly sure of the form of the guys in front of me, nor do I know their track records," said Harrington, who sits level on ten under par with England's Mark Foster.
"But I'll be doing my thing and hoping I can keep my name up on that leader board and that brings pressure to bear."
And after 30,721 spectators braved the rain and wind on day three, Harrington is hoping their support can lead to a 27th professional career title.
"The upside of having a home crowd behind you is you're getting carried along and you are winning the tournament," he said.
"There is the downside that if you're not playing well you feel disappointed, and you feel like you are letting people down.
"But having the crowd behind you can only be positive in terms of trying to win the tournament, no doubt about it.
"So I would say it's worth 20 per cent, 25 per cent help on your performance. It's significant."
Leading scores after the third round of the Irish Open at Royal Portrush on Saturday (GBR & IRL unless stated, par 72):
204 - Jamie Donaldson 68-67-69
205 - Anthony Wall 67-71-67
206 - Mark Foster 66-67-73, Padraig Harrington 67-67-72
207 - Paul Waring 69-65-73
208 - Craig Lee 73-68-67, Thorbjorn Olesen (DEN) 72-70-66, Fabrizio Zanotti (PAR) 69-71-68, Rafael Cabrera Bello (ESP) 71-67-70
209 - James Morrison 68-70-71
210 - Mikael Lundberg (SWE) 69-66-75, Francesco Molinari (ITA) 70-67-73, Richard Bland 68-69-73, Gary Orr 68-68-74, Mikko Ilonen (FIN) 66-72-72, Estanislao Goya (ARG) 70-70-70, Matthew Zions (AUS) 66-71-73, Edouard Dubois (FRA) 66-73-71, Simon Dyson 67-72-71, David Drysdale 70-70-70, Rory McIlroy 70-69-71, Andrew Marshall 66-71-73, Alejandro Canizares (ESP) 67-70-73, Lorenzo Gagli (ITA) 68-66-76
211 - Jeev Milkha Singh (IND) 65-71-75, Richie Ramsay 69-70-72, Ross Fisher 68-71-72, Michael Hoey 70-67-74, Oscar Floren (SWE) 66-72-73
212 - Robert Jan Derksen (NED) 69-71-72, Graeme McDowell 71-68-73, Gregory Bourdy (FRA) 65-67-80, Bradley Dredge 68-71-73, Richard Sterne (RSA) 70-69-73
213 - Christian Nilsson (SWE) 69-71-73, Peter Whiteford 67-70-76, Jorge Campillo (ESP) 71-69-73, Matthew Baldwin 70-69-74, Darren Clarke 71-69-73, Thongchai Jaidee (THA) 67-72-74, John Daly (USA) 70-71-72, Marc Warren 71-68-74, Jbe Kruger (RSA) 69-73-71
214 - Alex Haindl (RSA) 68-70-76, Gary Boyd 71-71-72, Romain Wattel (FRA) 69-70-75, David Howell 71-71-72, Ricardo Santos (POR) 69-72-73
215 - Mark Murphy 69-73-73, Stephen Gallacher 72-69-74, Steven O'Hara 69-69-77, Paul McGinley 69-70-76, Sam Little 71-68-76, Simon Thornton 70-70-75
216 - Emiliano Grillo (ARG) 68-74-74, Robert Rock 71-71-74, Damien McGrane 71-71-74, Shane Lowry 72-68-76, Phillip Price 71-70-75, Rich Beem (USA) 69-72-75, Lee Slattery 70-69-77
217 - George Murray 72-68-77, Joel Sjoholm (SWE) 70-72-75, Paul Lawrie 69-72-76, Marcel Siem (GER) 69-71-77, Johan Edfors (SWE) 72-68-77
218 - Mark O'Sullivan 68-72-78
219 - Joost Luiten (NED) 72-69-78
220 - Simon Khan 72-70-78
223 - Fredrik Andersson Hed (SWE) 68-73-82