Former world number one Justin Thomas closed with a brilliant eagle on Friday to tie overnight leader Taylor Moore for second.
Colombia's Echavarria earned his first 36-hole lead on the PGA tour, matching his performance of 64 from the first round to finish at 12-under overall, sinking seven birdies to shake off the blemish of a bogey on the par-four 12th.
Power carded eight birdies in a bogey-free second round to finish tied for fourth, three shots off the pace.
Min Woo Lee was the leading Australian after a one-under 69 left him equal 42nd.
Thomas was bogey-free as his second shot on the par-five 18th flew over 200 yards to land just a few feet away from the hole and the eagle, along with his four birdies, helped him move up five places in the leaderboard.
"I feel like you can make a lot of birdies out here if I keep driving it like I have," two-time PGA Championship winner Thomas said. "But so can everybody else. Just got to keep the hammer down."
World number two Xander Schauffele was also error-free after Thursday's unfortunate quadruple-bogey, sinking five birdies to improve to two-under overall on his 31st birthday.
A bogey on the par-four ninth dropped Eric Cole to fourth place at nine-under.
American Moore, who led by one shot after the first round, had a bogey on the par-four 11th.
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