American pair Bud Cauley and Tony Finau share the lead at the halfway point of the Valero Texas Open, but it was a disappointing day for Graeme McDowell as he shot a two-over-par 74 to fall back to six off the lead.

McDowell started his round two behind overnight leader Branden Grace and looked well placed to set up a weekend push; however five bogeys - three in his last four holes - damaged his ambitions. He's now two-under for the tournament.

Seamus Power is level par after a second consecutive 72 - enough to just survive the cut.

Cauley and Finau are tied on eight-under as the former, who is chasing a first PGA Tour win, fired a six-under-par 66 while Finau went one better with a 65.

Cauley struck six birdies in his blemish-free round, but Finau's card was more erratic, with an eagle, eight birdies and three bogeys keeping the scorers busy.

Australian Cameron Smith, who matched Finau's 65 as the lowest score of the day, Bob Estes and Kevin Chappell lead the chasing pack on seven under.

Scotland's Martin Laird is three shots off the lead after his 67 moved him to five-under

There were some high-profile names to miss the cut as Zach Johnson and Luke Donald will not be returning for the weekend, while Ian Poulter's failure to beat the even par cut-off means he loses his PGA Tour card.