Shortly after noon Thursday, with the temperature inching closer to 80 degrees, Meredith McGehee of the Campaign Legal Center parked herself in a shady spot across the street from the Longworth House Office Building.

Lawmakers streaming by, on their way into the Capitol for a day-long, topsy-turvy debate on lobbying reform, stopped to chat. Some were dismayed the bill didn’t go far enough. Others were angry it went too far — and wanted to scream about it.

“As a public interest lobbyist, you learn that giving Members the opportunity to yell at you can be very helpful,” the veteran reform advocate said. “Often Members of Congress have to be nice to everybody, so when they’re able to vent, it’s a relief that they finally get to be frank.”

For lawmakers from both parties turning up their nose at the bill’s tough medicine, it was a last chance to protest. At 1:08 p.m., Democrats put on a brave face and swallowed hard. Hanging together to approve a rule governing debate on the measure, they ended weeks of hand-wringing by their leadership, nervous that surprisingly stiff internal resistance would derail the overhaul package and, with it, a key Democratic campaign pledge.

The final showdown had come earlier that week in a two-hour meeting of Democratic leaders and some members of the conservative Blue Dog Coalition, who were threatening to block the rule over a proposed requirement that lobbyists disclose campaign checks they bundle for candidates. Leaders wanted the provision added to the broader package as an amendment but, according to an aide, won no new support in the meeting. There was talk as late as Tuesday that Democrats would have to pull the bill rather than risk an embarrassing defeat on the floor.

Then, on Wednesday, a breakthrough: The recalcitrant Blue Dogs agreed to support the rule if it set up the bundling measure as a stand-alone bill. Their hope, according to one senior Democratic aide, was if they could keep it out of the package, it would be ruled out of scope during conference negotiations, effectively killing it.

That strategy was rendered moot by the end of the day Thursday, thanks to a Republican scramble for the high ground in the debate. After opposing the rule, GOPers executed a swift pivot and began pushing changes to beef up the Democratic package.

When the bundling bill came up for a vote shortly before 2:30 p.m., Republicans put forward a motion to recommit that expanded its scope. Even as Democrats were breaking off to support the measure, Democratic lawmakers and aides, blind to Republican plans until they received the text of the proposal minutes before the vote, were rushing to make sense of it.

Republicans were claiming their measure closed a major loophole in the bundling legislation by widening its coverage to include contributions to campaign committees and leadership political action committees. Phone calls to outside legal experts helped Democrats confirm what they suspected: The original bill, authored by Rep. Chris Van Hollen (D-Md.), already covered gifts to those accounts. The GOP measure simply broadened the disclosure requirement to checks lobbyists arrange for outside political action committees, such as those for EMILY’s List or the National Rifle Association.

Republicans claimed victory when the motion passed, while Democratic leaders, breathing a sigh of relief that their measure was still intact, brushed off the change as meaningless. Minutes later, lawmakers from both parties overwhelmingly approved the underlying bill.

GOPers had another surprise in store. Two hours later, after debate on the broader package and sifting through a handful of amendments, Democrats got their first look at the second Republican motion to recommit. Again, they had only minutes to decipher it before the vote.

“Talk about whiplash,” said one Democratic aide close to the process. “There was a lot of confusion because we got it at the last minute and were trying to figure out how it affected everything. Members were confused about what it did.”

Republicans, as it turned out, had been refining the proposal over the course of the day. It began with two proposed changes to the bill that Democrats blocked Republicans from offering on the floor: closing a loophole that exempted lobbyists for public entities from a new gift ban and tightening restrictions for lobbyists who take a backward spin through the revolving door for jobs on Capitol Hill.

GOPers got an idea for an addition from a front-page story in The Washington Post that morning that focused on Democrats’ troubles living up to their promises on earmark transparency. To highlight the problem, Republicans added a provision to their motion requiring lobbyists to disclose in quarterly reports any earmarks they are seeking for clients.

Then, once Republicans pushed through their alternative to the bundling measure, GOPers stuck in a provision to include that version in the overhaul package. One hundred fifty-eight Democrats joined Republicans in support of the proposal.

The base bill then passed with wide bipartisan support, 396-22. Leaders from both parties rushed to claim credit for the accomplishment.

“The lobbying bill passed today is virtually identical to one passed by the Republican-led House last year — and in the few areas where it goes further than last year’s bill, Democrats have only Republicans to thank,” House Minority Leader John Boehner (R-Ohio) said in a statement.

Even as lawmakers were still voting on the Republican motion, Democratic leaders convened a press conference to tout their win. “When the Speaker’s gavel comes down, it’s intended to open the people’s house, not the auction house,” said Caucus Chairman Rahm Emanuel (Ill.).

McGehee was still outside, calling into her group’s downtown offices for updates. She said the “bidding war” that had transpired inside was the natural result of putting ethics reform debates on record.

“Much of the fight is trying to get this into the light of day,” she said. “Both parties are trying to clean up their profiles on these issues. So when you get the votes out in the open, reform advocates do pretty well, because the other side is so indefensible.”