Mitt Romney has a six-point lead on President Barack Obama, according to a Gallup poll of likely voters released Wednesday. He leads 51-45 among likely voters, and 48-46 among registered voters, according to a seven-day average.

Gallup's margin is large among recent polls; seven other national polls released in the last two days show margins varying from +3 Obama to +4 Romney.

The Gallup poll showed Romney at 50-46 on Tuesday and 49-47 on Monday.

The numbers do not reflect Tuesday night's debate, in which many observers concluded that Obama had a stronger performance than Romney, if only slightly.

In the first week of October, Romney was tied with Obama at 48 percent each, according to Gallup, which recently announced changes to its survey methodology.

This story has been updated to add context about earlier Gallup polling.

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  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • President Barack Obama and Republican presidential candidate and former Massachusetts Gov. Mitt Romney participate in the second presidential debate at Hofstra University in Hempstead, N.Y., Tuesday, Oct. 16, 2012. (AP Photo/Charles Dharapak)

  • Republican presidential nominee Mitt Romney, left, addresses President Barack Obama during the second presidential debate at Hofstra University, Tuesday, Oct. 16, 2012, in Hempstead, N.Y. (AP Photo/Pool-Shannon Stapleton)

  • President Barack Obama, left, speaks to Republican presidential nominee Mitt Romney during the second presidential debate at Hofstra University, Tuesday, Oct. 16, 2012, in Hempstead, N.Y. (AP Photo/Pool-Win McNamee)

  • Republican presidential nominee Mitt Romney and President Barack Obama speak during the second presidential debate at Hofstra University, Tuesday, Oct. 16, 2012, in Hempstead, N.Y. (AP Photo/David Goldman)

  • President Barack Obama and Republican presidential nominee Mitt Romney speak during the second presidential debate at Hofstra University, Tuesday, Oct. 16, 2012, in Hempstead, N.Y. (AP Photo/David Goldman)

  • HEMPSTEAD, NY - OCTOBER 16: Republican presidential candidate Mitt Romney (L) speaks as U.S. President Barack Obama (R) listens during a town hall style debate at Hofstra University October 16, 2012 in Hempstead, New York. During the second of three presidential debates, the candidates fielded questions from audience members on a wide variety of issues. (Photo by Shannon Stapleton-Pool/Getty Images)

  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • Republican Presidential nominee Mitt Romney (rear) and US President Barack Obama debate on October 16, 2012 during the second of three presidential debates at Hofstra University in Hempstead, New York. AFP PHOTO / Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

  • Republican Presidential nominee Mitt Romney (L) and US President Barack Obama debate on October 16, 2012 during the second of three presidential debates at Hofstra University in Hempstead, New York. AFP PHOTO / TIMOTHY A. CLARY (Photo credit should read TIMOTHY A. CLARY/AFP/Getty Images)

  • US President Barack Obama and Republican presidential candidate Mitt Romney both speak at the same time during the second presidential debate October 16, 2012 at the David Mack Center at Hofstra University in Hempstead, New York. AFP PHOTO/Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)

  • US President Barack Obama and Republican Presidential nominee Mitt Romney debate on October 16, 2012 at Hofstra University in Hempstead, New York. Undecided voters asked questions during a town hall format. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / TIMOTHY A. CLARY (Photo credit should read TIMOTHY A. CLARY/AFP/Getty Images)

  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)