LAS VEGAS — Republican Sen. Dean Heller and Democratic challenger Rep. Shelley Berkley quarreled over health care, immigration and tax breaks for oil companies in the second debate of their acrimonious campaign Thursday night.The encounter began with Heller proposing the candidates treat each other “respectfully” -- a notable request after millions of dollars of slashing, personal attack ads and a contentious first debate in Reno last month. Heller tried to cast himself as a champion of bipartisan, sensible solutions, while Berkley contended the Senator was really supporting big corporations like insurance and oil companies.“We need ideas and solutions in Washington, D.C., and we need someone who recognizes that and is willing to work with both sides,” said Heller, who was appointed last year to fill out the term of Sen. John Ensign after he resigned in a sex scandal. Berkley, a seven-term congresswoman from Las Vegas, defended her own behavior amid a Congressional ethics investigation of whether she improperly interceded to help the business interests of her husband, a nephrologist. “I'm working every day to make sure we create good-paying jobs right here in the state of Nevada,” Berkley said. “At a time when Nevada families need a champion in the United States Senate, my opponent is playing for the wrong side.”The live televised debate was interrupted by a five-minute power outage due to a violent storm tearing through Las Vegas. The power cut out just as Heller was arguing that the country needs more energy generated in North America.The contest is one of the most heated Senate races in the country, the focus of massive spending not only by the two campaigns but by outside partisan groups. Democrats see the race as one of their best opportunities to pick up a seat in the Senate, while Republicans hope to gain control of the chamber if Heller holds on and they take other open seats elsewhere. Polls have showed the candidates are neck-and-neck.The first question from moderator Mitch Fox was directed at Berkley, asking if, in retrospect, she would have refrained from voting on legislation to raise Medicare reimbursement rates that benefited her husband. “I don't think that I could have disclosed more and I don't think I should have abstained,” Berkley replied, saying it was one of 114 bills to improve health care she supported. “The people of the state of Nevada elected me to stand for them and fight for them.”Heller declined to take a swipe at Berkley on the matter, instead shifting to an attack on President Obama's health care law, which Berkley voted for. “Within five years you're going to be taken away from your doctor....and thrown in a government pool,” he warned.The two tangled over financial reform -- Berkley admitted a 1999 vote for legislation to deregulate banks was an error but blasted Heller for voting against the latest version of Wall Street regulation known as Dodd-Frank -- tax breaks for oil companies, and immigration. Heller was challenged over his support for English-only laws and legislation to end citizenship for children born in this country to illegal immigrants. The senator, who has aggressively courted the Hispanics who comprise 15 percent of Nevada's electorate, replied that he wanted comprehensive immigration reform. He said he backed that and English-only laws to help immigrants. “The principles that I'm trying to support is trying to make these people succeed. I want them to succeed here in this country.” Berkley pointed out that Heller voted against the Dream Act, which would allow people brought to the U.S. illegally as children to obtain citizenship if they serve in the military or graduate high school, and supports Arizona's controversial immigration law. Berkley herself was on the defensive when asked why she voted against a bill that would allow the opening of a copper mine in northern Nevada. She said she had sponsored the original bill but rejected the version that Republicans brought to the floor because it was larded up with unrelated measures. She said she wants to vote for a “clean” bill.Heller replied: “Only in Washington, D.C., can you say you're for a bill and vote against it.”Berkley pressed Heller on his support for both versions of Republican vice presidential candidate's budget, which would open Medicare to private insurance companies. “You don't fix Medicare,” she said, “by killing it.”Heller noted that his own parents depend on Medicare and Social Security and that he wants to find ways to preserve the programs.