Second-placed Liverpool moved on to 77 points with three matches to play. United have 80 points and four matches remaining.
FA Cup finalists Everton completed a successful Merseyside double over the North-East when they won 2-0 at Sunderland to move above Aston Villa into fifth place with 56 points from 35 games.
Second-half goals from Steven Pienaar and Marouane Fellaini secured victory at the Stadium of Light and left Sunderland in 16th place, one above Hull City who face Villa on Monday.
Liverpool took the lead with first-half goals from Yossi Benayoun and Dirk Kuyt. Substitute Lucas headed in the third three minutes from time.
Newcastle, who had Joey Barton sent off in the second half for a wild challenge on Xabi Alonso, remain in the relegation zone with 31 points from their 35 matches. With three games to play, they are three points behind Hull City.
Liverpool manager Rafa Benitez said his side could have scored more goals as they chase their first title since 1990.
"We have to wait for United to make a mistake and just have to keep going and we will," he told Setanta Sports News. "We have the right mentality and we will keep fighting."
BARTON APOLOGY
Asked if Barton deserved the straight red card, Newcastle's interim manager Alan Shearer said: "Yes. He apologised. He is now suspended for the rest of the season. We placed our trust in him and yes we feel let down."
Liverpool had skipper Steven Gerrard back in midfield after three games out with injury, but were missing striker Fernando Torres, sidelined with a hamstring strain.
Shearer dropped former England striker Michael Owen to the bench after nine matches without a goal.
He came on for the last 10 minutes, got a mixed reaction from his former fans and made little impact on the match.
Liverpool dominated the opening stages and went ahead after 22 minutes, although there was a touch of fortune about the goal.
Kuyt provided the cross and Benayoun, who looked to be marginally offside, scored with the ball bouncing in off his knee.
Six minutes later, Kuyt escaped Newcastle's defenders and scored with a brave diving header which gave Newcastle keeper Steve Harper no chance.
Lucas headed in the third goal which sent Newcastle to their third defeat under Shearer, whose two other games in charge have ended in draws.
Alonso, who hit the bar twice, was carried off after being clattered by Barton, back in the side for the first time since January 28.
