“ER” survived 10 seasons after George Clooney left the show and took his star power to the big screen. Just as the hospital drama pivoted to an ensemble cast, so too will the Senate, which appears poised to continue on without a breakout star as two of its biggest celebrities move on to bigger things.

The elevation of former Sen. Barack Obama (D-Ill.) to president and the expected nomination of Sen. Hillary Rodham Clinton (D-N.Y.) to be secretary of State will leave the Senate lacking in star power for the national stage. Senators who appear poised to try to step into those starring roles might be hard-pressed to match the glamour of the former first lady and the political phenom whose cult of personality began when he was a state Senator giving the keynote address at the 2004 Democratic National Convention.

“Obama and Clinton have profiles that have always been not just larger than life but larger than the Senate,” said one well-placed Senate Democratic staffer.

The staffer added, “This upcoming Congress has a chance to be one of the landmark Congresses in American history but more as a collective body, not as individuals. … [In the future,] kids may be reading in their textbooks about the 111th Congress, but they may be hard-pressed to name anyone who served in it.”

Even the biggest names remaining in the Senate have been diminished. Sen. Edward Kennedy (D-Mass.), the liberal lion of the Senate, can’t be counted out as a legislative force, though his battle with a brain tumor has limited his role as a public face for the Democrats.

Similarly, Sen. John McCain (R-Ariz.) has the national recognition to continue as a Senate celebrity, but he just lost the presidential election and his party is looking for new national leaders after even more bruising losses on the Congressional level.

McCain is easily the best-known Republican Senator and has always basked in the limelight. “He has always enjoyed a very positive relationship with the media … and the celebrity press corps,” such as Larry King and Barbara Walters, a senior Senate GOP aide said.

Regardless of McCain’s efforts to recapture the attention of journalists, the absence of Obama and Clinton offers room for any number of Democrats to try their hand at fame.

“I think there will be an opportunity for a new crop of Senate stars … to rise,” one senior Senate Democratic aide said. “With so many high-profile names in the Senate at once, it kind of sucked the air out of the room.”

Even the names of those Senators whose star power is expected to rise seem to rely on Obama’s popularity. Majority Whip Dick Durbin (Ill.) and Sen. Claire McCaskill (Mo.) are often mentioned as Democratic up-and-comers — but much of that speculation rests with their status as friends and early supporters of Obama’s presidential bid.

Durbin and McCaskill are “two of Obama’s biggest cheerleaders,” one Senate Democratic leadership aide said.

But the aide cautioned that there is room for more movement in the Democratic ranks.

“There are U.S. Senators that are going to step up and show leadership and fill that vacuum, but it’s going to take a while,” the Senate Democratic leadership aide said. “There are some people who are destined to become the new faces on the Sunday talk shows and have their [profiles] raised over the next two to four years.”

One senior Senate GOP aide agreed that the stars of the Senate galaxy might be determined by the media. “The more exposure you have on television, the more people are going to view you as a national leader,” the aide said.

The leadership aide and others said that besides Durbin and McCaskill, Sen. Bob Menendez (N.J.) is “a fast riser.”

Menendez, who is set to take over the chairmanship of the Democratic Senatorial Campaign Committee in the 2010 cycle, “is an extremely gifted orator, and he understands policy. And with his new position at the DSCC, he’s also going to be in the thick of politics,” the Senate Democratic leadership aide said.

Menendez, a tireless spokesman who rarely turns down a media request, is already the national face for Senate Democrats in Spanish-language news.

Competing with Menendez for the spotlight, however, will be outgoing DSCC Chairman Charles Schumer (N.Y.), who has been the butt of jokes about his penchant for seizing the limelight, particularly when there’s a TV camera around. Given that Schumer’s unstinting efforts haven’t made him the national name, it remains unclear whether he can break out without Clinton and Obama overshadowing him.

Other Senators mentioned as potential national stars are Virginia’s new Democratic duo Jim Webb and Mark Warner. As a Vietnam War hero, Webb has already achieved a national following as an author and for his Senate battle to expand educational benefits for veterans coming home from Iraq and Afghanistan. His newest book, “A Time to Fight,” came out around the same time in 2008 as Senate Majority Leader Harry Reid’s (D-Nev.) tome, “The Good Fight,” and continues to outperform Reid’s book on Amazon.com.

As a former governor from a reddish state, Warner has often been mentioned as a presidential contender and in 2007 was originally seen as one of the biggest threats to Clinton’s primary run.

But none of those people has cut the profile of hero to their own party and — importantly — bugaboo for the opposing party. Though Republicans often invoked Kennedy as the embodiment of evil liberalism, that has largely ceased because of his health concerns.

Instead, Republicans have been reduced to raising the specter of lesser-known Democrats. Even Clinton was off-limits during the presidential campaign given McCain’s strategy of wooing her supporters. Instead, McCain began running an ad in September attacking Obama’s “celebrity” and linking him to “out-of-touch Congressional leaders.” The ad featured pictures of Reid and Schumer, along with Sens. Byron Dorgan (D-N.D.), Patrick Leahy (D-Vt.) and Chris Dodd (D-Conn.) — not exactly George Clooneys.