When Gen. David Petraeus comes to Congress this week to give Members an update on the Iraq War, it will mark one of the few times this year that all three presidential contenders have been on Capitol Hill at the same time.

Sens. John McCain (R-Ariz.), Hillary Rodham Clinton (D-N.Y.) and Barack Obama (D-Ill.) are expected to take time off from their presidential campaigns to question Petraeus, who will appear before the Senate Armed Services and Foreign Relations committees on Tuesday. Ryan Crocker, the U.S. ambassador to Iraq, also will testify.

The duo head to the House Armed Services and Foreign Affairs committees on Wednesday.

Plenty of reporters, policy analysts, war protesters and others should be on hand for the hearings, as the three presidential contenders are expected to use their positions on those panels as a way to forward their ideas on Iraq.

McCain, the ranking member on Armed Services, will perhaps have the easiest time doing so — he’ll have an opportunity to present an opening statement and be the first Republican to ask questions.

But Clinton, who sits on Armed Services, and Obama, who has a seat on Foreign Relations, have far less seniority and will have to wait their turn.

Armed Services Chairman Carl Levin (D-Mich.) and Foreign Relations Chairman Joseph Biden (D-Del.) told reporters on a conference call Friday that there are no plans in either committee to let the Democratic presidential nominees ask questions ahead of more senior Members.

Levin added that he will work to ensure the hearing sticks to the issue at hand — the situation in Iraq — rather than become politicized.

Meanwhile, Capitol Hill security officials are focused on making sure everybody stays safe during the Iraq hearings.

Senate Sergeant-at-Arms Terrance Gainer, the man in charge of overseeing security in the chamber, said officials “will be vigilant” because it isn’t every day that a general and three presidential contenders arrive on Capitol Hill.

But at the same time, security efforts won’t be unprecedented. A Capitol Police spokeswoman described security efforts as “routine” and Gainer said the department is well prepared for the event.

“Business is never usual around here, so some days are a bit more hectic than others, and that will be,” Gainer said of Tuesday’s hearing.

Committee staffers are expecting much of the same thing. While Tuesday might make for a big day, it isn’t anything they haven’t seen before, because the Armed Services and Foreign Relations panels hear from important people pretty frequently.

“We really don’t have any unusual preparations,” said Tara Ardringa, the spokeswoman for Armed Services Committee. “We’ve gotten a lot of calls, but we do for most big hearings.”

But that doesn’t mean the committees aren’t taking some precautions. Knowing plenty of people are going to want to sit in on the testimony, the Foreign Relations panel is holding its hearing in 216 Hart Senate Office Building, one of the biggest committee rooms on Capitol Hill, according to panel spokeswoman Elizabeth Alexander.

And committee officials are urging the public to line up early, since seating will be first come, first serve. Panel officials also are working with the press galleries to coordinate and reserve space for the large number of reporters expected to be on hand, Alexander said.

Generals and would-be presidents aren’t the only ones prepping to have their voices heard this week. Prominent protesters, many of whom are experts on how things go down when the important people are testifying, also will be on Capitol Hill.

“What often happens in the hearings is they will reserve very few seats to the public,” said Gael Murphy, one of the founding members of anti-war group CODEPINK. “We are planning on going early, getting in line, waiting our turn.”

CODEPINK and other groups also plan to chat up the hoards of media expected at the hearings, Murphy said, pointing out anything they view as inaccurate in Petraeus’ testimony.

And people off Capitol Hill also are being urged to get involved. United for Peace and Justice, a coalition of various anti-war groups across the country, is asking supporters to flood Member offices with calls and faxes this week in a push to pressure Congress to cut off war funding.

“Regardless of what the details are of what he says, we want to put the pressure on Congress,” said Leslie Cagen, the group’s national coordinator. “Basically our point of view is that this war needs to end, and it needs to end now.”

Tim Taylor contributed to this report.