Many Americans are undecided about the 1980 presidential race, but Big Labor certainly appears to have made up its mind about candidates for seats in Congress.

The AFL-CIO has compiled the voting records of congressmen and has rated the legislators according to the frequency with which they have supported the AFL-CIO position on labor-related issues.

The labor federation says that between Oct. 1, 1979, and Aug. 6, 1980, Congress voted on 19 measures of importance to labor. The federation compiled each congressman's score on these 19 bills: "right" for those who agreed with the AFL-CIO and "wrong" for those who disagreed.

Curiosity directed my eyes to the line on which the AFL-CIO recorded the current labor record of Rep. John Anderson of Illinois. He was judged to have been right zero times, wrong twice and absent 17 times. His cumulative voting record since he entered Congress in 1961 was listed as Right, 52 times; Wrong, 138 times.

A separate AFL-CIO summary devoted to Anderson's record alone says that in 1961-62, Anderson voted against aid to depressed economic areas, against bringing more workers under minimum wage protection and against a plan to speed up NLRB procedures.

In 1963-64, Anderson voted against a public works program, against "worker and union protection" in a mass transit program and against providing vocational training for needy young people.

In 1965-66, Anderson voted against the repeal of a right-to-work law, something union men find it hard to forgive.

In 1967-68, he was finally judged "right" on something; he was against compulsory arbitration legislation and so was the AFL-CIO. But Anderson was judged wrong on a federal pay bill.

In 1969-70, he was listed as wrong on three key labor votes. In the next Congress, there were 18 bills important to labor, and Anderson was judged to be wrong on 13 of them (including two votes against food stamps) and right on five. During the 1973-74 session he again voted twice against food stamp bills and was scored wrong eight times, right three times.

During 1975-76, Anderson swung a mite closer to labor and was rewarded with a count of 11 wrongs and six rights. The AFL-CIO says he was "against funding for Humphrey-Hawkins full employment proposal" and "for a restrictive move against union political rights." In 1977-78, Anderson became a backslider and was scored wrong 13 times, right only three times. By 1978 he was considered a liberal Republican presidential hopeful by some people, but apparently that group didn't include union leaders.

The September issue of In Transit, the official journal of the Amalgamated Transit Union, noted that Anderson was considered a liberal Republican when he ran in the primaries against the likes of Ronald Reagan, John Connally and George Bush. But now, running as an independent, "he will have to endure closer scrutiny."

After examining his record, In Transit concluded that although Anderson is not a Neanderthal reactionary, nevertheless "on key economic, social and labor issues, Anderson seldom strayed from hard-nosed GOP policy."

Other ALF-CIO spokesmen agree that Anderson has not been a strong friend of labor and that Jimmy Carter is more deserving of labor's endorsement and support. However, it is not yet clear how much impact this will have.

The labor establishment is not supporting John Anderson, but it remains to be seen how individual union members will vote. Occasionally an organization's leadership thinks that it is leading a parade on Main Street only to discover that its rank-and-file members are marching down Broad Street.

We may never know what influence the AFL-CIO ratings have among business and professional people who do not think of themselves as "labor" but nevertheless sympathize with and support many of labor's goals. Labor's influence will be easier to identify in industrialized areas, where wage earners predominate. In fact, if Anderson wishes to turn the tables he'll be able to give the AFL-CIO a rating on the morning after the election.

Incidentally, if you would like to compare Anderson's labor rating with that of another legislator who is known as a liberal Republican, you can check Mac Mathias' line in the Senate table.

The AFL-CIO says that on the 19 votes important to labor in this Congress, Mathias was right 16 times, wrong zero times and absent three times. Mac's lifetime batting average with labor is 128 right and 37 wrong.

As we noted in a previous column, there are now several shades of liberalism and conservatism in the Republican Party, just as there have long been in the Democratic Party. "Liberal" is not nearly as precise a description as it used to be.