Senate Democrats refused to rule out filibustering President Bush’s pick to replace EPA Administrator Christine Todd Whitman on Wednesday and vowed to scrutinize every aspect of the administration’s environmental record in the process.

With control of Congress and the White House up for grabs in 2004, the debate over Whitman’s replacement at the Environmental Protection Agency will be shaped by the ambitions of Democratic presidential contenders and both parties’ need to energize their constituencies. Whitman announced her resignation in a letter to Bush Wednesday morning.

Leaders in the environmental community, in particular, will be watching closely to see what role the four Democratic Senators seeking their party’s presidential nomination play in the confirmation process. The quartet, Sens. John Edwards (N.C.), Bob Graham (Fla.), John Kerry (Mass.) and Joe Lieberman (Conn.), are eager to burnish their environmental credentials, and all hope to draw the green vote in the 2004 primaries. Graham and Lieberman sit on the Environment and Public Works Committee — the panel charged with vetting the eventual nominee — giving them the first crack at questioning Bush’s pick. Edwards and Kerry are expected to be equally vocal about Bush’s environmental record during the nomination proceedings.

“This is an example of where these guys in the process want to take whacks at Bush, and this is a legitimate issue,” said a top aide to a Democrat seeking the White House nomination.

Republican leaders will be engaged in double duty as they watch closely to see if Democrats try to block the nominee, while also keeping an eye on moderates within their own party who disagree with Bush’s environmental policy. Republicans hold a 10-9 advantage on the EPW panel, all but assuring Bush’s nominee clear sailing to the Senate floor for a vote. But Senate rules give the minority party-wide latitude when bills and nominees reach the floor for a full vote, and 41 Senators opposing an executive nominee effectively defeats it.

Democrats were careful Wednesday not to utter the word filibuster — a tactic they have successfully employed this year to block two of Bush’s judicial nominees — but made it clear it is an option.

“I will reserve all my options that I have on this nomination, just as I have on many others,” said Sen. Barbara Boxer (Calif.), a Democratic member of the EPW panel.

Sen. Max Baucus (Mont.), another Democrat who sits on EPW, was more blunt about a filibuster being triggered and said the White House “would be very wise to consult” Democrats when choosing a new administrator.

“They are going to need 60 votes, essentially 60 votes to get a replacement for her,” Baucus said.

At the very least, Democrats said they would use this opportunity to shed light on the administration’s environmental record, which Sen. Jim Jeffords (Vt.) — an Independent who serves as the ranking EPW Democrat — characterized as “so far out of sync with the rest of the country.”

Not only will the White House aspirants be in the spotlight during the nomination debate, but Capitol insiders will be watching to see what role Sen. Hillary Rodham Clinton (D-N.Y.) assumes. Clinton, a member of the panel who has made the environment a major part of her policy portfolio, said she plans to be “very forceful” in questioning the nominee to better understand that person’s views.

“I think that is one of the oversight responsibilities of the confirmation power that the Senate constitutionally exercises,” she said. “This will be an opportunity to review the administration’s record thus far and to ask, whoever the nominee is, their position and intention when it comes to a lot of these important issues.”

Clinton noted it won’t be just Democrats but also some Republicans who will have detailed questions for the nominee.

“There are certainly Republicans who share a commitment to the environment who serve on the EPW committee, and a vigorous vetting of this candidate could lead to bipartisan support or bipartisan opposition,” she said. “We don’t know.”

One of those Republicans is Sen. Lincoln Chafee (R.I.) who suggested it would be in the administration’s best interest to find a nominee with similar political views to the moderate Whitman.

“I think it is important,” he said. “This appointment was seen from the beginning as an olive branch to the moderate wing of the Republican Party.” The Rhode Island Republican also said he is not sure if he could offer his unequivocal support for a nominee if he sharply disagreed with the individual’s view on environmental policy.

“I will have to come to grips with that in the hours ahead,” Chafee said.

Republicans acknowledge the efforts to replace Whitman could be difficult if Democrats try to block the nomination and if support among some GOP Senators is weak.

“Democrats have made it very clear that obstructionism is the word of the day,” said Senate Republican Conference Chairman Rick Santorum (Pa.). “That is exactly what they are all about.”

“I suppose it is going to be hard because we got a few Republicans that are a little hard to keep with the majority,” added Sen. Craig Thomas (Wyo.), a Republican member of the EPW panel.

Graham and Lieberman were both careful not to say they would block Bush’s choice to head the EPA, but noted in separate interviews they will vigorously question the nominee.

“This administration has set the worst environmental protection record since the environmental movement began in the late ’60s,” Lieberman said. “We will use whatever clout we have, but the president is the president for now and it is his choice to make.

“We will question the nominee closely, aggressively and then decide how to vote,” the Connecticut Democrat added.

Graham, too, said it is Bush’s prerogative to pick whomever he wants to work in his administration, but added he plans to ask pointed questions of the nominee “either in the committee directly or by submitting questions” in writing.

While Chafee echoed a common theme voiced Wednesday by Democrats and Republicans that they hoped the EPA nomination wouldn’t turn into a partisan fight, he acknowledged that relations are strained between the two parties.

“The atmosphere is so poisoned to begin with that it is just one more conflagration,” he said.