By Richard Allen Greene
BBC News, Washington
The Bush administration has, until recently, been either clever or lucky in its choice of opponents.
Saddam Hussein, for all the talk about what a threat he posed to his neighbours and the United States, proved essentially a push-over when US tanks rolled towards Baghdad.
And Senator John Kerry was left standing slack-jawed when allies of the administration attacked what should have been his greatest asset in running against the president - his war record.
But things could be about to change.
President Bush's latest opponent is no ageing Middle Eastern strongman, no long-faced patrician senator, but a glamorous former spy out to tell how the White House has wronged her.
As the American networks have been putting it, Valerie Plame Wilson has broken cover.
Ms Plame is the CIA agent who was named in the media after her husband said the White House had misrepresented intelligence about Saddam Hussein's nuclear weapons programme.
The disclosure of her CIA link by columnist Robert Novak ultimately led to the conviction of Vice-President Cheney's top aide, "Scooter" Libby - though not for the leak itself, but for trying to obstruct the investigation.
Mr Libby, a key White House aide, blocked the leak investigation
The Libby trial revealed that at least four senior adminstration officials had leaked her name to the press in the summer of 2003.
On Friday, almost exactly four years to the day after the invasion of Iraq, Ms Plame testified for the first time about how the revelation of her CIA connection had affected her.
"My name and identity were carelessly and recklessly abused by senior government officials in the White House and state department" - which should have been protecting her, she said.
Press and public packed the hearing chamber, while hassled House aides directed latecomers to overflow seating next door.
Three protesters from the anti-war women's group Code Pink stood at the back of the room, displaying hand-made pink polystyrene crowns bearing slogans such as "Peace now".
Stick to beat Bush
But once Ms Plame showed up, all eyes were on her - poised and professional in her smart herringbone jacket and dark slacks.
Even the Republicans on the committee joked about being slightly awed by her.
Representative Lynn Westmoreland, whose gentle Southern drawl barely hid the hard line of his questioning, began by saying even the baseball stars who testified about steroid use in the sport had not drawn such a big crowd.
"I've never questioned a spy before," he said to chuckles from the gallery.
But Ms Plame deflected the apparent attempt to butter her up, responding simply: "I've never testified before."
In her, the Democrats have an excellent stick to beat the administration that has battered - or simply ignored - them for the past six years.
The camera loves Ms Plame, a striking blonde (out of a bottle, to be sure, but blonde nevertheless) with a dramatic story.
And - more by accident than design, certainly - the administration of George W Bush has cast her in one of the classic roles: that of the wronged woman.
Once upon a time, she would have been played by one of Hollywood's beautiful but hard stars - Bette Davis, perhaps.
'Hit in the gut'
The 10 Democrats who showed up for the hearing threw her one opportunity
after another to lay out her complaints.
When she found out the Novak column had blown her cover, "it felt like I had been hit in the gut ... I thought of my family's safety, the agents', the networks I had worked with".
She had been an undercover operative, she declared, even though at the time her cover was blown she was working at a desk at CIA headquarters: "When a general comes back to the Pentagon, he is still a general."
She was not responsible for sending her husband on the mission to Niger that undercut Mr Bush's claim Saddam Hussein was seeking nuclear bomb ingredients in Africa.
"I did not recommend him; I did not suggest him ... I did not have the authority," she said.
And whether the people who leaked her identity to the press knew she was under cover or not, "they knew I was CIA - that should have raised a red flag" about naming her.
Only two Republicans attended the hearing - Representative Westmoreland and the committee's senior Republican, Tom Davis - but they defended their turf as fiercely as the 300 Spartans who held off the Persians at Thermopylae.
Representative Westmoreland cornered her into identifying her husband as a Democrat, then asked Ms Plame her own political allegiance.
"I got a list of questions here I can't ask you," the Republican said, referring to limits the CIA had put on Ms Plame's testimony. "This wasn't one of them."
Reluctantly, she identified herself as a Democrat too.
Rep Davis tried to show Ms Plame's career had not been damaged by the Novak column (she continued to work at the CIA, though not, obviously, in her previous role) and to blame the CIA itself for failing to prevent Novak from publishing it.
But it was Ms Plame, not the Republicans, who left the lasting impression.
"I had no political agenda. Joe had no political agenda," she asserted. "We were both looking to serve our country."
That may be true, but the Democrats certainly have a political agenda - and in Valerie Plame Wilson, they may have found their messenger.
Expect to hear and see a lot more of her in the next two years.