Then his old boss, Senator Michael Bennet of Colorado, reluctantly took the helm of the Democratic Senatorial Campaign Committee, looking at another brutal map for Democrats eager to stay in control of Congress’s upper chamber. He had one demand: Keep Guy Cecil aboard. “It was critically important that Guy stay in the job,” said Mr. Bennet, now reunited with Mr. Cecil, the former chief of staff who spent the last months of his 2010 campaign sleeping in the senator’s Colorado basement. “He is just excellent at what he does.” Mr. Cecil’s return as executive director of the committee is notable in a city accustomed to political consultants cashing in for big money “downtown” — at lobbying firms and with influence peddlers off Capitol Hill. In 2010, Mr. Cecil helped engineer Mr. Bennet’s successful defense of his seat, one of the unexpected wins that kept Democrats in control of the Senate even as the party suffered a historic defeat in the House. Most assumed Democrats would lose the Senate as the 2012 season began. With Mr. Cecil directing forces, the party gained two seats. But do not tell the reigning Democratic political wunderkind that he has a tough job. That only gets him started. At 23, he was a Southern Baptist minister in Miami. Then he came out as gay, left a conservative church that would not accept him and went to Boston because it seemed diametrically opposite of the world he had fled. His first job was in retail, paying $19,990 a year. His grandmother had started the family’s hard-knock cycle, running from an abusive marriage in Ohio to Miami, where she raised five children as a waitress for 40 years. His father is a boat mechanic in South Florida. His brother, born with a malignant neuroblastoma, was not supposed to walk, if he survived his first birthday. He is 32 now, with chronic health problems — and two children. “I really have no need to complain about how hard my job is,” Mr. Cecil, 38, said with a shrug. Which is a good thing, because he could have a lot to complain about. After the struggles of 2010 and 2012, the road ahead for Senate Democrats does not look much smoother. Incumbents are likely to face tough races in the red states of Alaska, Arkansas, Louisiana, Montana and North Carolina. Democratic retirements in Iowa and West Virginia have opened new fronts for Republicans eager to avoid a third strike in their quest to regain Senate control. Both parties are awaiting a decision by Senator Tim Johnson, a Democrat, about whether to run again in South Dakota. Beyond that, freshman Democrats, swept to power in the Obama wave of 2008, face their first re-election campaigns in the swing states of Colorado, Minnesota, New Hampshire and Oregon. Only once in 75 years has the president’s party not lost seats in the midterm election of his second term. Mr. Cecil’s goal: “To hold the majority, that’s it,” he says. Rob Jesmer, who in 2012 was Mr. Cecil’s opposite number at the National Republican Senatorial Committee, called him “smart and relentless.” “I’ve got a lot of respect for him,” he said. Mr. Cecil’s approach to Senate elections goes back to the vicious 1998 re-election campaign of South Carolina’s Ernest Hollings, the last Democratic Senate victory in that state, and 2000, when he helped former Gov. Mel Carnahan of Missouri defeat John Ashcroft, a Republican, despite the fact that Mr. Carnahan had died in a plane crash three weeks before Election Day. Mr. Cecil tries to resist national political winds and tailor each campaign to the particular candidates and the states they are running in. Republican campaigns tend to ride national waves, running on broad national issues like the size and scope of government, the level of taxation and the defense of the homeland. Mr. Cecil had different ideas for different Democratic candidates. For instance, Heidi Heitkamp in North Dakota ran on “North Dakota values,” a languishing farm bill and essential air service to rural America. Sherrod Brown, practically buried under an avalanche of Republican advertising, ran as David against Goliath, even if he was the incumbent in Ohio.