Democratic presidential candidate Sen. Barack Obama (Ill.) is beginning to widen his advantage over Sen. John McCain (R-Ariz.), leading by a double-digit margin in four respected national polls released this week.

The RealClearPolitics average of recent national polls now gives Obama a 7.6-point lead, with Obama ahead in every survey included in the analysis.

The latest Pew Research Center poll gives Obama his widest lead, a 14-point spread. Polls conducted by Zogby International and Gallup as well as an NBC/Wall Street Journal survey all put the margin for Obama at 10 points. Other polls put the race at 2 to 9 points.

The Pew poll, a highly respected nonpartisan survey which had a margin of error of 2.5 points, finds that Obama’s lead has grown steadily since just after the national party conventions ended, when the race was about even. The latest showing for Obama reflects greater confidence in him on issues such as Iraq and terrorism, while Obama has widened his already substantial lead over McCain on his ability to handle the economy.

Doubt persists about McCain’s judgment, with 41 percent saying they see him as “having poor judgment” and just 29 percent reporting the same feelings about Obama. Since before the debates, more voters view Obama as “well qualified,” though McCain by a large margin is still viewed as having the better credentials to be president. Nevertheless, about half of all voters say either candidate would be “risky.” And the number who think McCain is too old to be president rose from about a quarter to a third of voters since before the debates.

Republican vice presidential candidate Gov. Sarah Palin of Alaska is viewed unfavorably by half of all voters, with 44 percent saying they see her positively. Sixty percent of women view her unfavorably.

The Pew poll was conducted Oct. 16-19 among 2,599 registered voters.