Instead of fighting the president directly, senior Republicans, such as Utah Sen. Orrin Hatch, are looking to the courts to reverse the legal argument Obama relied on to place Richard Cordray at the head of the new Consumer Financial Protection Bureau.
But Lee argues if the Senate doesn't stand up to the president's action now, it may see its power to block nominees erode permanently.
"We can't, as an institution, as a country, afford to allow one person to exercise power that does not properly belong to him," he said.
Lee's resistance began Thursday when he voted against the three nominees before the Senate Judiciary Committee. In two cases, his was the only vote in opposition.
Beyond this, Lee has refused to explain exactly how he will try to fight the president's picks, saying doing so would be bad strategy. He could simply vote against each person, or he could use Senate rules to delay action or force extra votes. But unless he has help, he can't block a nominee from eventually receiving Senate confirmation.
"If it's just me alone, it's not going to change much," said Lee. "I've talked to my Republican colleagues and I'm still talking to them constantly about the nature of the problem and what ought to be done."
GOP concern • Republicans on the Judiciary Committee are careful not to directly criticize Lee, saying he's operating within the Senate rules. Hatch even said, "It takes a lot of guts" to make such a stand, though he questions the political strategy.
"I worry a little bit. It is very apparent the president is running against Congress and sometimes it is good to wage battles even though you know you are going to lose," Hatch said. "But you have to take into that equation that the president is not waging a fair battle and he has a tremendous advantage."
Other Republicans demurred when asked if they would support Lee's plan to fight back.
"I think every member of the Senate has kind of got their own ideas on how to deal with this," said Sen. John Cornyn, R-Texas.
The top Republican on the Judiciary Committee, Sen. Chuck Grassley, R-Iowa, said he "certainly wouldn't discourage" Lee from opposing the president's nominees, but he won't follow the same course. Instead he said he's waiting for the 47 Senate Republicans to develop a unified plan.
"My position is, I'm going to wait until we have a caucus decision," said Grassley.
Like Grassley, Cornyn and others, Hatch is placing his hope on legal challenges, some already filed and others expected in the coming month from business groups that can argue the actions approved by the nominees in question are invalid because the president illegally placed them in power.
Senate Republicans are already planning to file a friend-of-the-court brief supporting that position.
"There will be a strong court fight on whether these appointments were unconstitutional, and I don't think there's any doubt they were," Hatch said.
Presidential action • On Jan. 4, Obama bypassed the normal confirmation vote to place Cordray in charge of the Consumer Financial Protection Bureau and to put three people on the National Labor Relations Board.
At the time, the Senate was on its standard holiday break, but holding short "pro forma" sessions every three days as a tactic to avoid the very thing the president did use his power to appoint people when the Senate was in recess.
Obama's legal advisers offered a novel justification, arguing that if the Senate had no intent to conduct official business, then a pro forma session is nothing but a charade. The president defended the move by saying Republicans held up these nominations, because they politically opposed the agencies, not because they had any concerns about the qualifications of the nominees.
"Every day that we waited was another day when millions of Americans are left unprotected," the president said.
Senate Republicans responded with fury, claiming the president made an unconstitutional power grab and has no authority to unilaterally decide when the Senate is in session or not.
Lee has been the most aggressive opponent. In the first judiciary hearing following the recess appointments, he announced his vow to fight all nominees until the president rescinds the actions, then he took his case to TV networks, conservative bloggers and even the House of Representatives.
On Wednesday, Lee spent 90 minutes making his case and answering questions before the House Oversight and Government Reform Committee. He called the day Obama made the appointments "a day of infamy" and said the president "thumbed his nose at the Senate."
He and other Republicans attacked the president's legal reasoning, noting the Senate passed a temporary tax cut in a pro forma session just days before Obama made the recess appointments.
One day after Lee launched his media blitz, Obama responded in his weekly radio and Internet address.
"One senator gumming up the whole works for the entire country is certainly not what our Founding Fathers envisioned," the president said.
Lee said his stand is not a partisan one, but an attempt to protect the separation of powers in the Constitution.
"I will continue to emphasize again and again that democracy is not a government of one," he said. "I would be just as hard on a Republican president who dare tries this nonsense as I am on this president."
While the Republicans continue to argue about the Senate's advise-and-consent powers, Democrats have followed the president's lead and hammered the GOP for standing in the way of the nation's business.
"The Constitution envisioned how a law gets passed. It never envisioned that you got a second extra constitutional bite of the apple to thwart its implementation when you didn't have the votes to beat it," said Rep. Gerry Connolly, D-Va. "You win, you lose. Fair or square."
Thomas Burr and Laura Schmitz contributed to this report.