Pelosi, in demanding how McConnell runs President Donald Trump's impeachment trial, always had the weaker hand because the Senate leader has such a strong grip on his majority. But McConnell, in repeatedly mocking Pelosi's delay in sending the impeachment articles across the Capitol, failed to dent any support within her own caucus.
As days turned to weeks, each leader dug in further, talking only through the media. After the House passed two articles of impeachment Dec. 18, the two never once met in person to negotiate.
The impasse ended Friday when Pelosi announced the House would vote in the coming days to send the articles and a team of House members to prosecute the case. House Democrats had no idea when she would make the move, giving her their implicit trust and exerting no pressure on her to give in to McConnell.
"Not in the least," said Rep. John Yarmuth, D-Ky.
Republicans said McConnell felt a similar lack of pressure, internally or externally.
"Generally, the answer is he doesn't feel much pressure on big moments," said Sen. Roy Blunt, R-Mo., a lieutenant in McConnell's leadership team.
Pelosi, 79, and McConnell, 77, are throwbacks to a different era when powerful figures in Congress could dictate outcomes. Washington may go many years before two such powerful figures run either end of the Capitol, let alone at the same time.
She is the most powerful House speaker in at least 25 years and, some historians have argued, possibly since Sam Rayburn, D-Texas, ran the House in the 1940s and 1950s. He is the most powerful majority leader in at least 30 years and, some have argued, possibly since Lyndon Johnson, D-Texas, ran the Senate in the 1950s.
Their personalities are night and day, but they have had similar goals.
She won her first House race in 1987 and never sought any higher office, methodically working her way up the ladder and taking the Democratic caucus reins as minority leader in 2003. He won his first Senate race in 1984 and took every tough job before taking over as Senate minority leader in 2007.
They're the perfect distillation of the raucous House and staid Senate: Pelosi, an impassioned liberal who recently declared her motto is "resting is rusting"; McConnell, the slow-walking conservative who overcame polio as a child and went on to write an autobiography titled "The Long Game."
They reached this moment after plenty of failure and whispers about their capability. McConnell remained stuck in the minority after overseeing three straight election disappointments, capped off by many preferred candidates losing in GOP primaries. He appeared out of touch with conservative activists.
When she faced a third straight loss for House Democrats, in 2014, Pelosi lashed out at critics, pointing to McConnell's previous string of defeats.
"Aren't you getting a little old, Mitch, shouldn't you step aside?" she said, mimicking a question a reporter should ask him. "Have you ever asked him that question?"
Finally, after circling each other in leadership posts for more than 15 years, the 2018 midterm elections left the Senate in GOP hands and delivered the House to Democrats: House Speaker Pelosi vs. Senate Majority Leader McConnell.
Their strategic moves start by getting a unified caucus behind them, then getting ready to just stand their ground.
"The Senate lends itself to patience, generally. McConnell's an incredibly patient, closely held guy," Blunt said.
McConnell put that to the greatest test when he refused to consider any nominee by President Barack Obama to replace Antonin Scalia on the Supreme Court after the justice died in February 2016.
Pelosi reclaimed the speaker's gavel last January in the middle of a 35-day government shutdown, refusing to negotiate over Trump's demands for border wall funding. He eventually crumbled, giving her a victory that forged a bond with more than 60 freshman Democrats, many of whom were initially unsure Pelosi was the right fit for the modern speakership.
"She has the unfettered trust, respect and admiration of the House Democratic Caucus," said Rep. Hakeem Jeffries, D-N.Y., a member of her leadership team.
Almost half of the GOP senators won office in the past five years, a younger crowd loyal to someone who they know only as majority leader.
McConnell and Pelosi have fiercely devoted supporters inside their respective caucuses, but they also benefit from legends who produce a good bit of fear in the rank and file.
"You saw what happened with Adam Smith," Yarmuth said.
Smith, D-Wash., is the House Armed Services Committee chairman who Thursday morning suggested it was time to give in and send the impeachment articles to the Senate. Less than two hours later, before even hearing from Pelosi, he immediately issued a long clarification pledging his full support.
"I looked at the story and I said, 'Whahhhhh. That's not what I should have tried to convey,' " Smith explained later that day.
Before issuing his correction, he sent the statement to Pelosi's office so she knew he was not undercutting her position. "Nobody threatened me with anything. I saw the reporting and did not think that was what I should have said, so I corrected it," he said.
Some Senate Democrats, unsure of exactly what Pelosi's strategy was, also broke ranks and said they were ready for the trial to start, including Sen. Dianne Feinstein, D-Calif., who hails from Pelosi's San Francisco.
By lunchtime Thursday, Feinstein clarified her position, supporting Pelosi.
McConnell saw those small cracks in the Democratic armor and ordered his troops to jab at the division. Republicans poked fun at Pelosi - who said during her impeachment speech that the House would be "derelict" if "we do not act now" - for delaying the trial over procedural demands for witnesses.
She sent signals that the end was near on this skirmish. "No, I'm not holding them indefinitely. I'll send them over when I'm ready. That will probably be soon," she told reporters Thursday.
As he left the Capitol on Friday, McConnell gloated a bit in having won this battle with his adversary. "Well, we've been anxious to get started for the last - how many weeks has it been now? And we'll get about it as soon as we can," he said.
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