Democrat Scott Murphy has surged to a narrow lead over Republican James Tedisco in the special election in New York’s 20th Congressional district, according to a new independent poll.The Siena Research Institute poll on Tuesday’s special election showed Murphy, a venture capitalist, with 47 percent of the vote, and Tedisco, the state Assembly minority leader who began the contest far better-known and in the lead, with 43 percent.The poll found that Murphy has essentially gained 3 points a week for the past month, while Tedisco has dropped 3 points a week for the past month.The poll of 917 likely voters, taken Wednesday and Thursday, had a 3.2-point margin of error.“This remains a very tight race, with intense campaign activity on both sides,— said Steven Greenberg, a spokesman for Siena.Greenberg said that Murphy, who started the race in late January as an unknown, has built his profile through advertising and his association with Sen. Kirsten Gillibrand (D-N.Y.), whom he is hoping to replace in the House, and President Barack Obama.“Murphy is now virtually as well-known to voters as Tedisco, and Murphy has a slightly better favorable rating, 49 to 38 percent, than Tedisco’s 48-41 percent,— Greenberg said. “Sen. Kirsten Gillibrand continues to be rated favorably by more than three-quarters of voters, while President Obama is viewed favorably by nearly two-thirds.”Voters believe the campaign has been quite negative — as evidenced by the rise in both candidates’ unfavorable ratings — but feel that Republican ads have been more negative than the Democrats’.At least nine in ten voters have seen or heard a commercial for both Tedisco and Murphy. Voters say Murphy’s ads make them less likely to vote for him, 30 percent to 23 percent. Two weeks ago, voters said 28 percent to 20 percent that Murphy’s ads made them more likely to support him.Tedisco’s commercials fare even worse with voters. Only 14 percent of those who have seen Tedisco’s commercials are more likely to support him, while 37 percent say the ads make them less likely to support Tedisco (12 percent to 28 percent two weeks ago). About half of voters said both candidates’ ads have no effect on who they are supporting, Greenberg said.Forty-two percent of voters credit Murphy with waging the more positive campaign, compared with 25 percent who say that describes Tedisco. Similarly, voters say 44 percent to 25 percent that Tedisco has been running a more negative campaign than Murphy. Nearly one in five voters says it’s both candidates. But when asked who they thought would win Tuesday’s election, poll respondents picked Tedisco by a 10-point margin. The upstate New York district has 70,000 more registered Republicans than Democrats.The final four days of the campaign should continue to be intense, as the attention of the national political parties keep their focus on the race. In a statement, Tedisco said his campaign’s internal polling shows him continuing to lead.