As Sen. John Kerry (D-Mass.) testifies before the Senate Foreign Relations Committee in hopes of being nominated Secretary of State, he's being welcomed by with (mostly) open arms. It's a stark contrast to the hostility that greeted outgoing Secretary of State Hillary Clinton yesterday.

Kerry himself noted partway through the hearing that "the one issue that seems to unite Republicans and Democrats is getting me out of the Senate."

It's the end of a long road for a lawmaker who has gone from Republicans' public enemy number one to Republicans' favorite Cabinet nominee.

That journey began in 1971 when Kerry, then a young Vietnam veteran, testified before the same Senate Foreign Relations Committee he sits before today.

"We feel, because of what threatens this country, not the reds, but the crimes which we are committing that threaten it, that we have to speak out," he said. "We are angry because we feel we have been used it the worst fashion by the administration of this country."

Thirty-three years later, his actions in that war and testimony afterwards would come back to haunt him, used by allies of President George W. Bush to smear him as a traitor and a liar.

Had Kerry won that election, he could well have bene leaving the White House after two terms right about now. Instead, he's been nominated for Secretary of State -- and embraced by many of the Republicans who attacked him in 2004.

An "excellent appointment," Sen. Susan Collins (R-Maine) has said. He "would sail through in the nominating process," agreed Sen. John Barrasso (R-Wyo.). And, Senate Minority Leader Mitch McConnell (R-Ky.) summed it up: “If they were to nominate Senator Kerry for something, he would be pretty broadly applauded on our side.”

Arizona Sen. John McCain (R-Ariz.) introduced his colleague as a man of "many talents and indefatigable persistence" whose work is "masterful." On the way into the hearing, he gave Kerry a hug.

Many of those same senators found Kerry's record on foreign policy deeply troubling in 2004. (With McCain, Kerry has sustained a deep friendship for decades, frayed by the 2004 and 2008 elections but in recent years reaffirmed.)

Part of Republicans' bonhomie has to do with their hopes of winning Kerry's Senate seat in a special election. But it goes deeper than that. Kerry, often criticized as too ambitious to take the Senate seriously, is now seen as having a more heartfelt appreciation of his role as a lawmaker who can reach across the aisle, as Paul Kane wrote:

Kerry has led efforts to forge deals on climate change and the “supercommittee” ’s bid for a grand bargain tackling the federal debt. He won approval for a nuclear arms treaty with Russia.

His big diplomatic moment came in the fall of 2009, when Afghan President Hamid Karzai was reeling from election results that kept him under the 50 percent threshold to avoid a runoff. Clinton dispatched Kerry to Kabul to persuade Karzai to call a runoff, and the Afghan leader relented only after Kerry delved into his own feelings of failure and despair about the 2004 outcome against Bush.

The respect and admiration Kerry has won in the Senate are the reason he's likely leaving it. It also means he gets to leave that hated Congress for a post that has made Hillary Clinton hugely popular -- if not with some Republican senators. For Kerry, it's also a testament that his political life has come almost full circle over the past four decades.