Republicans may find it hard to convince US blue-collar voters

President Reagan's coattails will be a heavy handicap for GOP candidates in the 1982 congressional elections.

This is the consensus that seems to have emerged within organized labor from meetings between union leaders across the country and AFL-CIO political strategists.

Many Republicans apparently are beginning to feel the same way. The recession , Mr. Reagan's fiscal 1983 budget, and high unemployment have put them on the defensive.

A ''growing fear of unemployment among working people'' is turning blue-collar workers back to the Democratic Party, says Thomas R. Donahue, secretary-treasurer of the AFL-CIO, who met with union workers in a series of regional conferences.

Many union members voted Republican in 1980 and helped send Reagan to the White House, helped give the GOP control of the Senate, and helped increase the party's representation in the House.

Earlier GOP predictions of Senate and House gains are now being discounted. Democratic victories in a number of marginal states are now considered much more likely.

Republicans were hoping that the pro-GOP election trend in 1980 would carry into 1982 and result in gains of five to eight Senate seats considered necessary to protect the party's control of the upper house in 1984. Now Sen. Howard H. Baker Jr. (R) of Tennessee, the Senate majority leader, says it appears that Republicans can count on gains of only two or three seats in what he terms ''a crucial year for Republicans.''

The Republicans now hold 54 seats in the Senate, the Democrats 45, and an independent, Sen. Harry F. Byrd of Virginia, the remaining seat. A GOP margin of control is hardly in jeopardy this year, when only 13 of 33 seats on ballots are held by Republicans. The threat to GOP control will be much greater in 1984 and 1986 when more Republican than Democratic seats will come up for grabs.

Meanwhile, labor's political hopes -- and expectations -- have risen considerably as economic conditions have worsened in recent months.

''Those brave enough or foolhardy enough to run on a Reagan program face a steep uphill battle in the fall,'' Mr. Donahue says. ''One out of four blue-collar workers faces layoff this year. Polls show that there has been a major shift in . . . measurements of satisfaction with the Reagan administration. That is going to be reflected in the congressional elections.''

John Perkins, director of AFL-CIO's Committee on Political Education (COPE), says that the situation in 1982 is similar to that in 1958, an election year in which the Democrats gained 13 Senate seats. Mr. Perkins predicted Democratic gains in the fall, but refused to go further than to say that the Democrats may pick up some Senate seats. It is ''not probable, although it is possible,'' he says, that the gains will be broad enough to return control of the Senate to the Democrats.

While some political analysts predicted earlier that a continuing conservative trend would give the Republicans control of the House, forecasts now call for Democratic gains of as many as 40 seats this fall.

Republicans, although worried, do not concede that the party is losing as much blue-collar backing as unions say. They point out that Reagan continues to have what they call ''inherent personal support'' among the public, including union members who fear inflation. The GOP contends this will help Republican congressional candidates in the fall.