CHICAGO, May 8--Senator Eugene J. McCarthy suffered a setback in Tuesday's Ohio primary when the Minnesota Senator's supporters won only three of the ten contested seats on the Ohio Democratic national convention delegation.

There are 115 delegates from Ohio. The other 112 votes belong to Senator Stephen Young (D-Ohio), who is not committed to any of the three presidential candidates.

In Colorado, where several thousand Democratic precinct caucuses met on Monday evening, Vice-President Hubert H. Humphrey appears to have taken a substantial number of them, but not a majority.

According to the Rocky Mountain Times (Denver), Humphrey captured 40 per cent of the precincts--to McCarthy's 30 per cent and Kennedy's 20 per cent. Colorado's 35 votes at the Democratic National Convention are still very much in question.

Benjamin C. Stapleton, chairman of the Humphrey Steering Committee, said tonight in a telephone interview, "We feel confident that Humphrey got a majority of the delegates to the local convention; though McCarthy's people did very well."

McCarthy showed strength in Boulder (home of the University of Colorado) and in the middle-class suburbs of Denver. Humphrey got most of his support from mining and industrial areas like Pueblo and Colorado Springs.

Minnesota, lowa

In Minnesota and lowa, McCarthy forces turned out many political novices for neighborhood caucus votes, and a well-organized McCarthy effort in Colorado produced unprecedented turn-outs in many areas. The energy in the McCarthy camp put pressure on the Humphrey forces to bring out the vote. Together they came up with the highest voting figures for precinct caucuses in Colorado history.

The McCarthy effort began in Boulder last November, when a group--mainly from the University of Colorado--formed the Colorado Conference of Concerned Democrats.