Second round leaderboard:
-12 B Snedeker (US), J Day (Aus) Selected others: -10 L Donald (Eng) -8 P Mickelson (US) -7 M Laird (Sco) -5 T Woods (US), B Davis (Eng) -4 P Casey (Eng) -2 I Poulter (Eng), R McIlroy (NI) Par P Harrington (Ire) +1 J Rose (Eng)
Padraig Harrington hopes to improve his form before October's Ryder Cup
Padraig Harrington has said he will add a European tour date to his schedule after missing the cut by one stroke at the Deutsche Bank Championship.
The Irishman finished level par after hitting a 68 in his second-round, finishing level par overall.
England's Luke Donald hit five birdies as he moved to within two shots off the lead with a second-round score of 67.
American Brandt Snedeker and Australian Jason Day lead the pack in Boston, both players on 12-under-par.
Tiger Woods gave himself a fighting chance of earning a wildcard place from US Ryder Cup captain Corey Pavin on Tuesday after hitting an impressive 65 to move to five-under for the tournament.
"I figure if I play two good rounds and win the tournament, I should be all right," Woods said after his round - one of the best of the day.
"I'm still learning to put this thing together. I'm going to have off days."
Meanwhile, Northern Ireland's Rory McIlroy plummeted down the leaderboard as he fired a second-round 76.
McIlroy's five-over-par round, 12 worse than Friday, left him 10 shots behind the leaders.
The 21-year-old bogeyed his opening hole and suffered four more bogeys and a double bogey.
Scotland's Martin Laird could not match his opening 66 but remains well-placed following a round of 69.
That leaves, Laird, who lost in a play-off with Matt Kuchar in the Barclays FedEx Cup last week, in a tie for 19th place.
Harrington's disappointing display will call into question European captain Colin Montgomerie's decision to add the three-times major winner as a wildcard pick for next month's Ryder Cup.
But Harrington told reporters that he will look to add a European tour date to his schedule in an attempt to improve his form.
"As much as I'd like a break, I still want to be competitive going into the Ryder Cup," he said.
"I'll definitely play before now and the Ryder Cup. What are the three [European tournaments]? I don't even know, I'll have to have a look."
The three European Tour events before the Ryder Cup are the Dutch Open, Austrian Open and Vivendi Cup in Paris.
Justin Rose also fell foul of the cut with a score of 73 in his second round, leaving him one-over-par overall.