He won't be here this year, the short man with the ever-present pipe and the lopsided smile, the man who could almost always work things out and get the legislature to do things his way.

Marvin Mandel is gone, and without him, everything is going to be a little bit different in the statehouse.

The legislative session, which began yesterday, will be the first in 25 years in which Mandel will play no major role. And as the suspended governor sits at home, awaiting word on his appeal of his political corruption conviction, a dozen different officials will be trying to pick up pieces of the power he left behind.

These jostlings are likely to result in new power coalitions, depending on which legislative leaders choose to align themselves with Acting Gov. Blair Lee III and his programs, and which legislators choose to oppose the chief executive, seeking instead some other power base.

The outcome of these maneuverings should determine what individual or what coalition of individuals will emerge as the controlling force during the 1978 legislative session. In the Mandel years, there was no real question on this issue: The legislature was part of a monarchy, and Mandel was the monarch.

But even in Mandel's last few years, legislators were chafing more and more under the system of one-man rule; Lee may find it impossible to take charge the way Mandel once did.

While all this is being sorted out, however, a lot of people will be doing a lot of experimenting. Furthermore, 1978 being an election year, all 188 legislators, the acting governor and a few other key officials will be competing for a larger share of the spotlight as well as a larger share of the power.

Going into this competitive, chaotic arena, most of the major actors have a good idea of what roles they would like to play. How well they succeed at playing these roles, how well they dodge the obstacles thrown in front of them will probably determine how much influence they will have when the session comes to a close.

For Blair Lee III more than anyone else, the 1978 legislative session will be a critical proving ground. With Mandel sitting at home waiting for word on his appeal of his federal mail fraud and racketeering conviction, Lee has a chance to run things his way.

He is also no stranger to the legislative process, and during his years as lieutenant governor and Montgomery County state senator he gained the respect of many legislators for his handling of complex bills on fiscal matters.

As governor, also, Lee will have a very good platform on which to display his various legislative initiatives - a governor always commands more media attention than a mere legislator.

This situation could backfire, however, if too many of Lee's initiatives fail to pass the legislature, or are modified out of existence. "I expect Blair's going to have a very modest program," predicted House Speaker John Hanson Briscoe (D-Mary's).

"He's got a good excuse for it," Briscoe added. "He's finishing a man's term and, but for Marvin Mandel's conviction, the state has been wellrun." What Briscoe did not add is that too ambitious a legislative program could result in highly publicized legislative failures.

Senate President Steny H. Hoyer (D-Prince George's), one of Lee's chief rivals for the Democratic gubernatorial nomination, has other problems to contend with. His proposals just don't get the kind of attention Lee's do.

Also, Hoyer will have to somehow reconcile his role as gubernatorial candidate - and Lee rival - with his role as Senate president - and Lee helpmate. If he cooperates with the administration, and helps Lee's bills through the legislature, he enhances Lee's gubernatorial chances. But if Hoyer obviously and consistenly sabotages Lee's programs, he risks being labeled an opportunist. "You can't sabotage administration programs without appearing to be playing politics," Briscoe pointed out.

Then there will be other, more subtle political minutes being danced. Many powerful legislators, like Baltimore's Harry McGuirk and Briscoe himself, wouldn't object to being placed on some statewide ticket or other, as candidates for attorney general or lieutenant governor.

So many of the upcoming votes by these legislators on such prominent issues as the death penalty, abortion and property tax reform may be taken as much to please one gubernatorial hopeful or another as to further their own personal beliefs or those of their constituents.

"I think it's going to be a little bit chaotic down there," mused state Sen, John J. Bishop Jr. (R - Baltimore County). "There are so many factions, a fractionalization of the political spectrum . . . and you don't have a Mandel . . . to pull people together."