For as long as anyone can remember, the presiding officers of the Maryland General Assembly have extended a courtesy to the state's governors, introducing the executives' bills in the House and Senate.

But this year, House Speaker Michael E. Busch (D-Anne Arundel) has decided to break with tradition. Busch won't be introducing bills by Gov. Robert L. Ehrlich Jr., the state's first Republican governor in more than three decades. Since Ehrlich can't introduce bills, the task will be left to the House minority leader for the next four years.

To outsiders, this might seem a minor breach of protocol. But in a capitol where custom is equated with civility, where decorum tempers rough-and-tumble debate, Busch's simple action has some insiders atwitter.

"Del. Busch should take his bat and ball and go home," said John Kane, the state GOP chairman. "It's a big sandbox, and it now has legitimate competition on both sides, so it's time to learn how to behave like adults."

Busch's decision and the reaction to it are examples of the new partisan tone in Annapolis as the governor and the Democratic-controlled General Assembly struggle to strike the right chord in a new era of divided government. Each side is carefully scrutinizing the actions and omissions of the other, and messages are divined where perhaps none are intended.

Legislation that affects people all over the state can live or die over small perceived slights, said Matthew Crenson, a Johns Hopkins University political scientist.

"Failing to follow the perceived proper procedure demeans other participants in the political process who don't get what they deem to be the respect their offices deserve," Crenson said. "It's an unnecessary way to cause offense."

When Ehrlich, for instance, sprawled across the House speaker's podium a few days ago, conducting business with lawmakers after the chamber had adjourned, some viewed it as a lack of respect for the separation of powers, instead of a governor merely trying to catch up with old friends: Ehrlich served in the House from 1987 to 1994 and became close with, among others, Busch.

"In the governor's defense, he's a low-key and friendly guy, and he genuinely feels at home in the House chamber, but he shouldn't have done that," said House Majority Leader Kumar P. Barve (D-Montgomery). "It's not appropriate. We wouldn't do that in the governor's office."

Busch said people should not read much into his not sponsoring the governor's bills. "It's more a matter of form over substance," he said. "Yes, the speaker has always put the governor's bills in, but we haven't had a Republican governor in nearly 40 years."

House Minority Leader Alfred W. Redmer Jr. (R-Baltimore County) was similarly sanguine. "The bottom line is that the governor is going to have his legislative package introduced," he said.

In the governor's office, however, some were vexed. "It is the speaker's prerogative, but I'm disturbed by that change," said the governor's chief lobbyist, Kenneth H. Masters, a former House member. "I know the governor's not thrilled with it either."

Masters yesterday had some explaining of his own to do.

This week, the governor introduced two major bills affecting crime and education policy without briefing the Democratic chairmen of committees that will debate them. The next morning, members of the GOP caucus were brought up to speed by Masters, but Democrats remained in the dark.

It was an oversight that baffled some Republicans, who realize that Ehrlich's initiatives can't pass without Democratic support. And it had Senate President Thomas V. Mike Miller Jr. (D-Prince George's) second-guessing his decision to stick with tradition by introducing the governor's bills.

"Every senator and delegate knows that if you are presenting an important bill to a committee, you go to the chairman well in advance," said Del. Jean B. Cryor (R-Montgomery). "In Annapolis, there are a lot of sins you can commit. Some are mortal; some are venal. Surprising and embarrassing a chairman -- that's mortal."

"It's a breach of protocol," said Miller. "If they're going to party-line everything and treat Democrats and Republicans differently, then Speaker Busch's action becomes appropriate."

Masters apologized to the committee chairmen yesterday. "It clearly was a very critical oversight, and I take full responsibility for it," he said.

He chalked it up to the fact that Ehrlich's staff has been overwhelmed since taking office less than three weeks ago.

"There's a lot of sorting out that has to be done," Masters said. "No one has a living memory of what it was like the last time we faced these circumstances and what constitutes normality."