When she brought her Pretty Woman smile to the Capitol in May, few of the star-struck fans who squeezed in to see Julia Roberts had even heard of Rett Syndrome.

But she spent a day explaining how the neurological disorder afflicts young girls, and got lawmakers from the House and Senate to talk about it, too. 

In the world where celebrities mix with politicians, that's pretty good work for a day —especially if lawmakers agree this fall to boost funding for Rett research from $3 million to $15 million, as Roberts has asked. 

Yet with more stars descending on Washington, critics wonder whether the trend has gone too far — say, when Kermit the Frog testified on animal research. 

Star backing is no guarantee a particular bill will pass, and last week provided a perfect example. For months, Ted Danson, Rob Reiner, Barbra Streisand, Christie Brinkley and other stars wrote lawmakers urging them to vote "no" on the White House plan to bury nuclear waste under Nevada's Yucca Mountain. 

Last week, the Republican-led House voted overwhelmingly in favor of the Yucca project. Senators on Tuesday did the same — handing a major victory to President Bush. 

Experienced staff claim lawmakers are open to persuasion from movie stars and shoe salesmen alike, and that, ultimately, decisions are made on merits. Still, having a big star can help. 

"It depends on how much credibility a star has. If they have a lot, it can be influential," said Alison Buist, a staffer for Sen. Gordon Smith (R-Ore.) who handles issues dear to celebs —education and health. 

In what will probably set a new standard for celebrity activism, U2's Bono recently returned from a 12-day trip with Treasury Secretary Paul O'Neill through Africa, where the rocker and the Republican discussed Third World debt. 

The trip won broad praise, and even conservatives in Congress, including retiring Sen. Jesse Helms (R-N.C.), are becoming open to the idea of helping poorer countries. 

Kevin Richardson of Backstreet Boys, a native of rural Kentucky, learned about mining's impact on forests during a fly-over with Robert Kennedy Jr. 

But the pop star's June 6 appearance on Capitol Hill exposed the resentment some lawmakers feel toward celebrities who venture onto their turf. 

One Hill skeptic noted jokingly that Richardson's "Just Within Reach Foundation" Web site touts his recent appearance on Celebrity Fear Factor and includes numerous "glamour" shots of Richardson, not coal fields. 

"It's just a joke to think that this witness can provide members of the United States Senate information on important geological and water quality issues," said Sen. George Voinovich (R-Ohio), who boycotted the hearing rather than listen to the teen heartthrob.

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