Steve Cotterill's side moved four points clear at the summit on Tuesday after a 3-1 win over Port Vale, while the two sides immediately behind them suffered defeat.
A trip to Scunthorpe United gives Swindon the chance to bounce back this weekend, although Mark Cooper's men are not having a great time of it on the road of late.
Tuesday's 2-1 loss at Oldham Athletic was their second successive defeat away from home.
MK Dons have begun to stutter in recent weeks with just one win in their last four league matches and ending that run will not be easy against a Gillingham side who are six unbeaten in all competitions.
"There will be a reaction," he told the club's official website. "We haven't lost that many games this season and the best teams will bounce back when they do.
"It's a big three points up for grabs for us and although it's going to be another tough game, we're going to have to go there with confidence."
Chesterfield are their nearest challengers and they host bottom club Leyton Orient on Saturday, while ninth-placed Fleetwood Town travel to a resurgent Crewe Alexandra.
They are not in action this weekend, though, placing even more emphasis on Colchester United's trip to Oldham, and Yeovil Town's clash with Doncaster Rovers.
