WASHINGTON -- When word began to circulate recently that Sen. David Boren of Oklahoma might resign to become president of the University of Oklahoma, some chills of apprehension ran through the Democratic Party.
It is not that Boren is considered an irreplaceable icon within his party. On the contrary, he put some noses out of joint in the White House last year when he balked at President Clinton's energy tax proposal, then voted against the budget bill even after Clinton had yielded on the issue.
But Democratic professionals are beginning to look at the possibility that their losses in the Senate elections in November might run as high as four or five seats, not the one or two that had been the conventional wisdom for the last year or so.
The Senate is now 56-44 Democratic, so the Republicans need a net gain of seven seats for control. That seems beyond reach, but the same thing would have been said at this same point the last time they captured the Senate in 1980. Moreover, even a loss of five seats would give enormous leverage to conservative Democrats such as Sen. Richard Shelby of Alabama, who sided with the Republicans against Clinton on key budget votes last year.
The context for the Democrats has been unfavorable from the outset because they have 21 seats at stake compared with only 13 held by the Republicans. But the situation has been made more uncertain for them because of campaign developments and polling results that continue to show some of their long-established incumbents less than safe.
The most striking change, of course, is that in Maine, where the retirement of Senate Majority Leader George Mitchell has made a safe Democratic seat anyone's guess. The contest there pits the state's two members in the House, Democrat Tom Andrews and Republican Olympia Snowe, against one another.
There are four other Democratic seats where retirements have opened doubts that might not have existed otherwise. The departure of Sen. Dennis DeConcini of Arizona, wounded by the Keating Five episode, has made Republican Rep. Jon Kyl the favorite. In Michigan, Ohio and Tennessee, other Democratic retirements have left the situations essentially a tossup.
Then there are several Democratic incumbents who are at least nominal favorites for re-election but still considered vulnerable to one degree or another. In Maryland, for example, Paul Sarbanes is favored over Republican Bill Brock, the former senator from Tennessee, but Sarbanes has never been a vivid political leader and polls show him less than unbeatable.
The situation is similar with Sen. Frank Lautenberg in New Jersey, being challenged by Chuch Haytaian, the speaker of the Assembly, and in Pennsylvania, where Harris Wofford is favored but hardly invincible against Rep. Rick Santorum. In Virginia Sen. Charles H. Robb would be no better than an even bet against Oliver North, if he is the Republican nominee as expected, and a less-than-even if James Miller, former Reagan budget director, is the GOP candidate.
There appear to be only two Republican-held seats in corresponding jeopardy -- those of the retiring David Durenberger in Minnesota and Slade Gorton in Washington, whose approval ratings continue to be modest.
At this point, the shape of the Senate campaign is still far from clear. To some degree, the Democratic outlook will depend on whether the economy continues to improve -- always an asset for the party in power. But their prospects also could turn on how such complex issues as health care reform play out over the next few months.
Clinton himself probably can have little direct effect on the Senate campaign. Although he clearly helped Rep. Dan Rostenkowski in his primary in Chicago early this month, there is abundant evidence that the preference of a president doesn't necessarily translate into anything at the polling place.
So the Democrats remain clear favorites to hold the Senate but they have no reason to be complacent.