The Black Cats remain seven points off the automatic promotion places with four games left to play, with the play-offs looking likely.
While the side are winless in four, they did gain a valuable point at title favourites Hull City on Tuesday evening in what was an encouraging performance.
And Leadbitter wants to see the side build-up some further momentum over the final weeks of the campaign, and believes the side need to remain calm in their pursuit of a place in the Championship.
“Let's see where the next two weeks go,” he said.
"Let's go and win all four games, that's what we have to do, but to start with we have to put in another good performance against Accrington and win the game.
"Then we have to go into the next one and let's see how we do. I do believe that's Hull done, so let's see how Peterborough go and try and put the pressure on.
“We have to go into the last four games to win, but our performances have got to be on par so if it's the play-offs we go into it playing well.
"We can't go into it not playing well - we need to go in with confidence, playing well and the way we want to attack.
"I'm experienced enough now to know what we need to do. We need to stay calm, because I know what it takes.
“We have to just continue being confident and playing well,” he continued.
“Tonight was a good performance, we have to do that, take a step back and let all the noise from outside of us go on.
"That always happens - we're a big club so that will always happen. We need to stay calm and keep sticking to what we're good at and our positives.”
The 2-2 draw at the KCOM Stadium came after a strong away performance, with Sunderland dominating the game for large spells.
And while recent results haven’t been as desired, the performances have been encouraging – leaving Leadbitter confident that the Black Cats can win their final four games.
“I thought Charlton the performance was good but we lost the game, which happens,” he explained.
"Wigan wasn't good enough, the performance wasn't good enough and we deserved to lose.
“At Blackpool I thought the performance was very good and we deserved to win the game.
“Tonight, the performance was good. We could have won it, but it could have gone either way. That's the fine lines of football.
"But three of the last four performances I thought were good. We deserved more points, but let's be honest - we kind of let ourselves down a bit regarding results, especially in the Wigan game.
"But we've got four games to go and we've got to go and win them all - and I believe that [we can].”