A new independent poll on the Philadelphia mayoral race had Rep. Chaka Fattah (D) in the lead, but with a free-spending businessman closing fast.

The Keystone Poll of 252 registered Democrats, conducted Jan. 24-29 by Franklin & Marshall College, found Fattah ahead of the Democratic primary field with 26 percent. Businessman Tom Knox — the only candidate to have advertised extensively so far — was next with 22 percent. Former City Councilman Michael Nutter was third with 12 percent, followed by state Rep. Dwight Evans (10 percent) and Rep. Robert Brady (8 percent).

The poll had a 6.2-point margin of error.

“Care should be exercised in interpreting these results as the candidates are still not well known, only one candidate has started television advertising, and the sample size is small,” pollster Terry Madonna cautioned in a memo.

But Knox’s progress is unmistakable. He was polling at 1 percent in the previous Keystone survey on the mayoral primary in July.

The May primary is likely to determine who succeeds term-limited Mayor John Street (D) in the highly Democratic city.

— Josh Kurtz