Washington — Once again -- in Michigan on Saturday -- Sen. Edward M. Kennedy will seek to prove his point: That President Carter can be defeated in the race for the Democratic nomination because of his unpopularity in the major industrial states.
The Massachusetts senator's win over Mr. Carter in the April 22 Pennsylvania primary was too slim for him to cite it in support of his "how I will win" thesis.
Now, sources in Michigan say that even if the senator gains a victory in the April 26 caucuses there it will probably be too close for him to use it as an example of big-state Carter vulnerability.
The pre-caucusing assessment, from veteran Michigan political observers, comes down to this:
One -third of those who will be caucusing are believed to be Carter supporters.
Another one-third are for Senator Kennedy.
The battle is over the remaining one- third of uncommitted voters.
"Both sides have called the 41,000 [actually 41,717] registered Michigan Democrats who wil take part in the caucusing at least twice -- and they have called the uncommitted one-third four or five times," one Michigan observer reports.
Why are only 41,717 Democrats taking part?
In brief, because the Democratic organization in Michigan decided to include only registered Democrats in the primary.
Last fall, the state Democratic Party began registering voters for the April primary. But by the time registration was closed in February, only that number of Democrats had signed up -- Michiganders were not used to having to register to take part in party primaries.
Detroit Mayor Coleman Young, a black, is the major leader in the Carter camp. The United Automobile Workers Union hierarchy, including its president, Douglas Fraser, is working for Senator Kennedy.
Growing unemployment in Michigan, particularly in the auto industry, would appear to be helping the senator.
But Mr. Young, together with most of the party's state and local leaders, provides the driving force for a formidable Carter organization.
The President is spending more money than Senator Kennedy in the state -- partly because he has more funds available. The Kennedy win in Pennsylvania was not impressive enough to start a heavy flow of new money into his campaign.
The "caucus" label for the Michigan contest is somewhat of a misnomer. The registered Democrats who turn out actually will be voting. But instead of going to polls, they will be going to county "caucuses" where they will be given a ballot.
Most of the Democrats who registered are from the bigger cities. Will this heavily urban group be more likely to vote for Senator Kennedy, since Mr. Carter usually draws better in rural areas? Or will the Democratic "bosses" who support the President in Michigan be able to persuade them to vote for him?
The viability of the Kennedy campaign may hinge on the outcome.