Washington (CNN) -- The Pentagon report on gays and lesbians in the military has been simmering for weeks but hits the full boil Tuesday.
Pentagon officials will turn up the heat when they travel to Capitol Hill to hand out advance copies of the report and to brief staff members of the House and Senate Armed Services Committee in the morning.
A few hours later Defense Secretary Robert Gates and Joint Chiefs Chairman Adm. Mike Mullen will hold a afternoon news conference at the Pentagon about the report and about why they support changing the present "don't ask, don't tell" policy.
The report includes a poll of active-duty military and families, and sets out how the Department of Defense can implement the policy change if Congress votes for a repeal..
Surveys were sent to 400,000 military personnel but a big majority either didn't want to or didn't bother to respond. The Pentagon received 115,000 replies -- about 28 percent.
The authors of the report say they went beyond the survey, with town-hall-type meetings, a separate survey of military families and discussions among small groups of a dozen or fewer soldiers and Marines. There was even a way to enter anonymous comments in an online box.
To make sure that the report reflected the opinions of gays and lesbians who might fear their statements could cost them their careers, the Pentagon used a private firm to seek out their opinions.
The audience for the report officially is just one person, Gates himself. But he will pass it along to members of Congress and make it public. The whole country gets a front-row seat as the debate heats up in the Senate Armed Services Committee, which holds hearings on Thursday and Friday.
The authors of the report say they delivered the goods. Co-author Army Gen. Carter Ham calls it the most comprehensive personnel policy assessment in the Defense Department ever.
Ham recently said his job was in his words, "to assess the impacts upon effectiveness, readiness, unit cohesion, recruiting and retention should repeal occur."
He said that the report also is contingency planning, "understanding those impacts, (and) develop a plan for implementation so that if the law is repealed and the policy changes the department is prepared for that."
Ham will likely face tough questioning from prominent Republican Sen. John McCain of Arizona, who has criticized the report, saying it should have asked whether a policy change was the right thing to do, rather than how it should be implemented.
"I want to know the effect on battle effectiveness and morale, not on how best to implement a change in policy.," McCain told CNN's Candy Crowley on Sunday. "I don't think that's a lot to ask when we have our young men and women out there serving and fighting, and tragically some of them dying."
McCain will get another crack at Ham on Thursday when the Armed Services Committee hearings begin.
For some senators, the wait for the report had provided political cover, a reason not to commit to either side. After Tuesday there is no place to hide and senators will be under strong pressure to make their views public.
Off Capitol Hill, groups for and against the policy change are readying their final lobbying efforts.
Alexander Nicholson, executive director of Servicemembers United, an organization of gay and lesbian troops and veterans, says he is optimistic that senators will read the report and clear the way for gays and lesbians to serve openly in the U.S. military.
"I think for a moderate category of centrist members (of Congress) this is really going to be the lynch-pin. A lot of people who have hinged their vote of the contents and outcome of the report," Nicholson told CNN. "I think its going to be an hour-by-hour and day-by-day unfolding of this and as we go along ... on Tuesday when the report comes out,on Thursday hopefully when the hearings get scheduled, we'll be able to see and recalculate the chances of this happening."
On the other side, Elaine Donnelly, founder and president of the Center for Military Readiness, said the present policy should remain and holds out hope that Congress won't rush to decide in order to consider a repeal during the lame duck session.
"I predict members of the Congress, members of the Senate, are not going to be stampeded," Donnelly told CNN.
She blames President Barack Obama for taking the issue too far.
"There is no benefit to the military," Donnelly said. "This is a political promise from the president, made to LGBT (lesbian, gay, bi-sexual and transgender) activists groups. He is determined to deliver on that promise at the expense of the Armed Forces."