Four straight wins have put Nigel Pearson's side firmly in contention to challenge for a top-two finish.
Leicester could strengthen their grip on an automatic promotion place when they host Wolves on Thursday night.
Marshall insists the feeling in the Foxes dressing room is positive as the players enter the final few months of the season.
"There's definitely a buzz around the place," the England Under-21 international told the media ahead of the visit of Wolves.
"There's a buzz because it's getting closer to the end of the season and we've put a good run together at a good time to put ourselves right in there.
"We are well in contention and the games are getting less and less. Hopefully, we can stay there. That's the challenge now.
"We've had a good run of wins and, hopefully, we can keep that going.
"The confidence is high. We are winning games and the end of the season seems to be getting closer now, whereas at the start of the season it felt far away."