SILVERSTONE, England - Jenson Button has hit back at McLaren supremo Ron Dennis after he warned the out-of-contract 2009 Formula 1 champion to "try harder".Speculation about the 34-year-old's future has intensified since Dennis told British TV: "Button is a highly paid GP driver. Yes, we're not giving him the best car, but he could do his bit."McLaren's new team boss Eric Boullier is also making no secret of his discussions with other drivers on the grid; said to be among them are Button's fellow champions Fernando Alonso, Sebastian Vettel and Lewis Hamilton.'GIVE THE BEST'Boullier told Britain's The Telegraph newspaper: "It's my job to be in touch with the drivers. Let's say some drivers on the grid, yes, I am talking to them."Button, however, suggests it is not fair only to point at the drivers and took issue with Dennis' plea for him to "try harder". He told told the UK's Daily Mail: "I think everybody has to try harder, the whole team, we all need to try harder."We're working hard but to get back to the front we all have to try harder, from the management down, and get the best out of ourselves. It hope that is what everybody is doing - I definitely am."The British driver was "looking forward" to the start of the Honda era but Boullier warned that McLaren could not simply expect its looming works engine deal to power the team back to the front of the grid."Everything has to be perfect," Boullier said. "We need to get all the stars aligned, which means the best drivers, best teams, best expertise, best engineering, everything the best."Then it will work."Stay with Wheels24 for the 2014 British GP this weekend.