We are the only team along with City with any sort of chance of catching Liverpool - we are in a title race - ok we could be in a better position of course however to right us off completely and dismiss us I think is a bit unfair. Liverpool may be in the middle of a bit of a wobble, who knows how they will react over the next few games - lots can change and plenty more points to win.Challenging for the title implies a good chance of winning it. At the moment, Liverpool are favourites with City an outsider. Spurs are not even in the equation, all statistical models have Spurs at sub 5%. Of course anything can happen in football, but when it comes to general performance and remaining fixtures, Spurs aren't in the picture for the title.
City's chances of a title challenge are hanging on a thread and one bad result could basically kill any chance of it. So no, I wouldn't say City are challenging for the title either, and if you insist on them being challengers its a very weak challenge.
Generally speaking you can say a team is challenging when you get to the business end of the season, usually the last 10 games give or take, and are 1st place or a few points from 1st place. 6 points behind in January is not a title challenge by any sensible definition, otherwise the term title challenge would become meaningless because so many teams would be within it that never got close to winning the league.