Mayor Martin J. Walsh, who hasn’t yet said if he’s running for re-election next year, increased his campaign spending last month, including doling out more than $50,000 on consultants, new campaign finance data show.

He continues to have significantly more cash in the bank than City Councilors Andrea Campbell and Michelle Wu, who have already announced they are running for mayor in 2021.

In September, Walsh’s campaign spent more than $90,000, according to state records. That amount represents an increase in expenditures compared to recent months; the campaign spent more than $29,000 in August, and more than $33,000 in both June and July. May saw the campaign spend more than $530,000, but that figure included a half-million-dollar donation to the Boston Resiliency Fund, which was set up to help those most in need during the COVID-19 pandemic.

Some political observers say Walsh’s September campaign finance spending could represent a ramp-up to a re-election bid in next year’s mayoral contest.

“An uptick in his spending indicates he’s not leaving, it looks more like a preparation,” said Louis DiNatale, a Massachusetts pollster.

Ray La Raja, a political science professor at UMass Amherst, said politicians who are Walsh’s age “are always running for something.” (Walsh is 53.) La Raja said he wouldn’t be surprised if the Walsh campaign is spending money on focus groups.

“He’s trying to see how tough the race is going to be,” said La Raja.

Candice Nelson, a government professor at American University, said “you can at least assume he’s considering” a re-election bid.

“Why else would he be doing this?” Nelson asked of his campaign activity.

She added, “We’re a year out, if he’s going to run, it’s probably time to start gearing up.”

Last month, the Walsh campaign paid SKDKnickerbocker, a Washington, D.C.-based political consultant and strategic