Dean Heller, a three-term congressman from Nevada, took the oath of office for the U.S. Senate on Monday, appointed by the Silver State's governor to replace John Ensign, who resigned his post earlier than expected in the face of an Ethics Committee investigation into an affair he had with a top aide's wife.

The swearing-in of the chamber's 100th senator will not change the closely divided body, as both Ensign and Heller are Republicans, but it could give Heller a leg-up in the hotly-contested 2012 election against Democratic Rep. Shelley Berkley, an election in which control of the Senate hangs in the balance.

Heller is already the odds-on favorite in any GOP primary; some Nevada politicos say former assemblywoman Sharron Angle, who lost an earlier House race to Heller, could run again. Angle lost a Senate race to Democrat Harry Reid last cycle.

Heller, a Mormon and Carson City native, is a former finance and securities analyst, working for a time as a stockbroker and broker/trader on the Pacific Stock Exchange before entering politics in 1990.  In a recent letter to supporters, Heller touted his vote against the Troubled Asset Relief Program (TARP).

The formal swearing-in ceremony got underway a little after 2pm EDT, as the gathering of senators waited for a tardy vice president. Senate Majority Leader Harry Reid, sporting a whopper of a black eye and right arm in a sling from a running accident last week, escorted his fellow Nevadan down the center aisle.  VP Joe Biden, in his capacity as president of the Senate, swore in the towering Heller, as the entire GOP leadership looked on.

It was an early present for the former secretary of state, coming one day before Heller's 51st birthday. With his wife, Lynne, at his side, the couple and their four children and one son-in-law greeted Vice President Joe Biden, D-Del., as he approached them afterward in the Old Senate Chamber for a ceremonial reenactment for the cameras.

"What a good looking family, and now I know why," exclaimed a beaming Biden to Heller's wife as, in typical trademark Biden fashion, the former senator-turned-VP held court.

"The longest walk in Washington is from the House side to the Senate side," Biden joked to reporters, then turned to the newest senator to size him up. The vice president, glancing down at one of Heller's pregnant daughters, quickly discovered he had something in common with the Republican, aside from his Democrat son-in-law.

"Daughters are wonderful, but granddaughters are even better," Biden, a grandfather many times over, told Heller, "Granddaughters always love their pops."

And reveling in the adoring females in Heller's family, the ever loquacious Biden ventured on. "First of all, God made a mistake," the VP dared, suddenly peaking the interest of the handful of reporters present, though he quickly added with a grin, "It's a joke!" To hearty laughs from Heller's family, Biden went on, "What I think should have happened, God should have spared fathers and had our daughters born beautiful, cute, and adorable, and when they turn age 12 or 13...turn them ugly as sin."

The joking Biden just kept the laugh lines coming. "I always voted for public housing, but I never knew it was this good," he said with a chuckle, as he invited the newest Senate family over to the vice president's residence, the historic Naval Observatory, something he said he and his wife, Jill, "always do with new members."