Beth Myers is seen at the Romney 2008 campaign office in Boston in April 2007. (Elise Amendola/AP)

Beth Myers, the adviser Mitt Romney tapped to lead his search for a vice presidential running mate, is so familiar with the presumptive Republican nominee that she often speaks for him in strategy sessions at the campaign's Boston headquarters.

In Romney’s 2002 race for Massachusetts governor, it was Myers, then a stay-at-home mom after a career staffing campaigns and practicing law, who played the candidate’s Democratic opponent in debate rehearsals.

After he won, Romney lured Myers back into the workplace, first as his chief of staff in the governor’s office and later as campaign manager for his 2008 presidential bid.

This time, it was Myers who directed Romney’s meticulous preparation for a seemingly endless cycle of debates during the Republican primary season. And now, after effectively clinching the GOP nomination, Romney has assigned Myers her most important — and secretive — task yet: overseeing the vetting of a running mate.

“Beth is a lawyer, she’s a logical thinker, she’s very methodical in her approach to problem-solving, she’s well organized. . . . But I think more important than that is that she has the trust and confidence of the governor,” said Eric Fehrnstrom, a senior adviser to Romney.

“She walks with a heavy shoe fall because people know that she has the trust of the governor and that she in many respects speaks for him.”

Myers, 55, an early protege of George W. Bush strategist Karl Rove, will be behind what is expected to be the first major presidential-style decision Romney will make. In an interview Monday, she said Romney will want “to hear a lot of voices, and he wants to get all the information he needs to then make his choice.”

Rove said Myers is up to the task. “She is capable of taking a large volume of information and distilling it, and she’s inexhaustible,” he said.Romney told ABC News’s Diane Sawyer that he has no specific deadline for making his selection, but that “it would certainly be by the time of the convention.” His wife, Ann, told Sawyer that this past weekend “was the first time we seriously really talked about it.”

Myers’s colleagues said she is skilled at reading people, looking beyond the paper record for intangibles that might indicate whether someone would have chemistry with Romney.

In the 2008 campaign, she struggled to manage a sometimes chaotic team and did little to prevent the warring of opposing strategists. But she maintained the candidate’s trust throughout.

Romney is expected to try to keep his short list and the search process under wraps, and Myers is an obvious choice for a task involving secrecy. On a largely leak-proof campaign, she is considered by colleagues to be particularly discreet. She rarely grants interviews to reporters and, unlike some other Romney advisers with roots in Washington, is not known to gossip about politics.

Myers, who has two dogs and three cats as pets at her Brookline home, is known at the campaign headquarters for her pop culture references. She is as versed on the latest tribulations of Don Draper in “Mad Men,” one aide said, as she is the political landscape in key swing states.

Myers was raised in Upstate New York and graduated from Tufts University with a degree in English. She has worked on campaigns around the country. Her first was in 1980, when she was in charge of voter identification programs in rural counties across Texas for Ronald Reagan’s presidential bid. Her boss that year: Rove, then a young operative on the make.

After law school at Southern Methodist University, Myers and her husband settled in Massachusetts, where she worked as chief of staff to former state treasurer Joe Malone. In 1998, she retired from politics to stay at home to raise her two children, then 5 and 7 years old.

Five years later, she returned to Beacon Hill to work for Romney, and she, Fehrnstrom and Peter Flaherty, a senior adviser to Romney, formed a close partnership. After the 2008 election, the three founded a consulting firm, the Shawmut Group. One of their marquee clients was Republican Scott Brown, whom they helped win the Senate seat of the late Edward M. Kennedy (D-Mass.).

Colleagues expect Myers’s low-key approach to make the process go smoothly. “She’s not out taking her helmet off, spiking the ball in the end zone so people can see who scored,” Flaherty said.