Bradley Wright-Phillips's first-half penalty looked to have done enough to propel the Red Bulls up to third in the table and give them an ideal warm-up for next week's visit of Arsenal.
However, the 27-year-old Lenhart pounced in timely fashion to salvage a point for the Earthquakes at the Red Bull Arena.
Mike Petke's side, who host the Premier League giants in a pre-season friendly next Saturday, took the lead shortly after the half-hour mark through Wright-Phillips, who coolly converted a penalty for his 17th of the season.
The 29-year-old was mere millimeters from his brace just minutes after the restart, firing a Lloyd Sam cross narrowly wide of the mark.
It proved a sign of things to come, however, as Lenhart drew the visitors level in the dying minutes of normal time to deny the hosts third place in the standings.