Guess who's coming to dinner after all?

After being invited to make the keynote speech at the Democrats' annual fund-raising Jefferson-Jackson Day dinner tonight, presidential aide Midge Costanza was "disinvited" by state party chairman Sen. Joseph T. Fitzpatrick, and then re-invited by Democratic National Committee member Pat Jennings. Jennings reinvited her yesterday after polling the steering committee of the party.

At this point, it looks as though she's coming.

"The division will last a lot longer if I don't go," Costanza said yesterday.

"If indeed she does come, she certainly will be treated with courtesy and civility by me," said Fitzpatrick, who took the unprecedented step of disinviting her in a speech on the Senate floor Thursday because she had criticized two party leaders for voting against the Equal Rights Amendment.

"This is Virginia, and one thing we learn early in life in Virginia is how to be gracious," said Fitzpatrick, who on Thursday said he might bar the door to Costanza if she showed up. He said later that he had made the comment in jest.

Costanza was criticized by Fitzpatrick Thursday - not by name, as prohibited by Senate's rules, but as "this person" - for comments published in the Roanoke Times and World News. Costanza was quoted as saying of House Majority Leader A. L. Philpott and House Democratic Caucus leader C. Hardaway Marks that "they should be ashamed of themselves for falling for the propaganda" of ERA opponents.

Costanza does not deny the accuracy of the quote, but said the implication of the story that she planned to speak only about the ERA and that she named Philpott and Marks specificially was wrong. She had not heard of them before, she said, and made her comment in response to a question about their having voted against the ERA.

Fitzpatrick said he had checked the accuracy of the quotes by asking other reporters about the reputation of the reporter who wrote the story.

"I really think there's been a terrible overaction," Costanza said yesterday. "I want the opportunity to meet the people of Virginia and I want them to meet me. I'm really looking forward to meeting Mr. Philpott and Mr. Marks."

She said that even President Carter had noticed the ruckus because he told a group of college editors she was addressing yesterday morning that he was glad she had the opportunity to talk to them because she'd been "losing other engagements."

Jennings, a former congressman who chaired the committee in charge of arranging the dinner, said that of the six Democratic National Committee members who made up the committee, four wanted Costanza to come; one, Sandra Duckworth, took no position and Fitzpatrick was the sixth member. Of the steering committee members he contacted, nine wanted Costanza to come, five did not, and "one or two" did not take a position.

Meanwhile, two Republican leaders leapt into the fray by sending Costanza a flowery letter inviting her to address the Republican caucus "at your convenience." The Republicans have been enjoying this whole squable, watching the other party's public dissension with glee.

The letter, signed by House Minority Leader Del Jerry Geisler (R-Carroll) and Minority Whip Del. Ray L. Garland (R-Roanke), was clearly composed by Garland, whose propensity for the English language in its most grandiloquent form is well-known.

"We hardly think that the mild opprobrium expressed by you of certain worthy gentlemen well-known to use was of sufficient magnitude to justify the outburst against you," they were, "We are persuaded that it was the painful result of the end-of-the-week, end-of-the-session fatigue which overcomes even the most mild mannered of our colleagues.

"While the respect, admiration, and affection that we in the Republican Caucus feel for the Hon. A. L. Philpott and the Hon. C. Hadaway Marks borders on veneration, we have ourselves had cause to express our exasperations with said gentlemen in terms similar to those employed by you. In fact, we have heard worse things said about thegentlemen in question.

"It is our conviction that the gentlemen are framed in the rich prodigality of nature. While we might disagree with any form of abuse employed against them, we will nonetheless defend to the death, your right - or anyone's - to abuse them. In fact, we have never known, them to be deterred by abuse."

After inviting Costanza to address the Republican Caucus "at any length - on any subject," they added, "If you would care to abuse further said gentlemen - or to extend that abuse to the Hon. Joseph T. Fitzpatrick - or others - we will stop our ears . . . With high consideration Madam, we have the honor to be, Your most obedient servants . . ."