Mumbai: Joe Root expects Alastair Cook to continue to lead England for "a few years to come" amid rising speculation on the future of the 31-year-old as test captain.

The left-handed opening batsman triggered doubts about his captaincy when he told the Cricketer magazine that he did not know "how much longer I am going to carry on. It could be two months, it could be a year".

He was forced to clarify his comments on the eve of the opening test of the five-match series against India at Rajkot and said he was doing the job on a series-by-series basis.

But with England trailing 2-0 after three tests, Cook's future has come under renewed speculation.

The 25-year-old Root is England's best batsman, vice-captain and seen as a natural successor to Cook, who had to leave his newborn daughter and family behind in October for a test series in Bangladesh.

Root said he had seen no indication from his captain to suggest he was contemplating giving up the job and said the team's batsmen had let their skipper down.

"I think he is coping all right," Root said of Cook.

"He's very professional and you don't really get much from him in that respect. I imagine it must be quite tough being away from a new child and family and everything.

"You could put a lot of blame on Cooky but actually it is the responsibility of the batters to make those big scores. You can blame whoever you want, but we have to take responsibility for our own game."

Cook, who surpassed Michael Atherton's England record of 54 matches as test captain after the first test in Rajkot, replaced Andrew Strauss as skipper in 2012.

He has led England to 24 victories, including a 2-1 series win over India the last time they toured the South Asian country in 2012.

"I think he is pretty set on captaining for a few years to come and I hope he does because I think he is a brilliant leader and I've really enjoyed playing under him," Root said.

"I'm quite happy with the role I'm playing at the moment and genuinely, honestly I think he is the right man.

"I hope we get these results we want in the last two games, and we can put right what has been quite a frustrating last couple of weeks."

Mumbai's Wankhede Stadium will host the penultimate test of the series from Thursday, while the final test will be played in Chennai from Dec. 16.