FOR JIMMY CARTER and Ronald Reagan, Tuesday in Wisconsin and Kansas proved to be a day of many happy returns. For their opponents -- all of them -- in both parties, the results from those two primaries varied only individually in the degree of bad news.

For Sen. Edward Kennedy, Mr. Carter's sole surviving challenger after the withdrawal of Gov. Jerry Brown, Wisconsin meant that whatever momentum he had picked up in Connecticut and New York was both fickle and ephemeral and given to spluttering stops -- and maybe new starts. Pennsylvania could very well be the last official act of Sen. Kennedy's challenge to Mr. Carter. Pennsylvania is urban, ethnic, union and Catholic -- just the kind of place where Edward Kennedy was supposed to beat Jimmy Carter this year. Four Years ago, Mr. Carter's victory in the Pennsylvania primary effectively won him the nomination. It could very well do the same thing in 1980. For Gov. Brown, Wisconsin marked the end of the 1980 road, as he said in his valedictory.

For George Bush, the day's only real consolation was a tighter lock on the Republican designation as the standby equipment in case of a major foot-slip by Gov. Reagan. And it will apparently require a very major obstacle for the Californian to trip over at this stage of the primary schedule. The question of Mr. Bush quickly becomes where he can beat Mr. Reagan in the upcoming primaries in Pennsylvania, Texas, Indiana, North Carolina, Tennessee and the District of Columbia. If Pennsylvania, on April 22, follows the pattern of New York and Illinois in supporting Ronald Reagan, then the George Bush candidacy is probably over, too.

For Rep. John Anderson, a disappointing third-place in Wisconsin, a state where he spent large amounts of both money and time, means only one thing: a third-party effort or involuntary retirement from the contest. Mr. Anderson, one of the principal congressional sponsors of public-financing legislation that had the stated goal of removing the influence of money from campaigns, has indicated real interest in a third-party run. He also makes frequent reference to his "71,000 contributors" and his intention of consulting with them before he makes any decision on what to do. So, apparently even with matching public funds, campaign contributors are still listened to by some candidates.

We have already outlined some of the legal and logistical difficulties in organizing a third-party effort. If Rep. Anderson or anyone else is serious about such a project, then the passage of time is most definitely not their principal ally.