Speaking to the media after the launch of Labour’s Climate Recovery Plan, Mr Sarwar said he “takes a lot of heart” from the progress the party has made in his five weeks as leader, but added: “our issue is time”.
It comes as a new survey published by Ipsos MORI on Wednesday showed that voters’ net satisfaction with Mr Sarwar’s performance was +26 per cent - 55 percentage points higher than the last rating of his predecessor, Richard Leonard - and only three points lower than that of Nicola Sturgeon.
But the same polling suggested that Labour could lose as many as five seats in the election next month, securing only 18 per cent of constituency and list votes.
New polling for The Scotsman published on Thursday also suggested support for Labour was static, despite its Mr Sarwar’s widely-praised performance in last week’s BBC debate.
Mr Sarwar rejected one reporter’s suggestion that he might be losing sleep over the polls, joking: “I think I'm looking pretty fresh”, and defended his party’s efforts in the campaign so far.
He said: “I'm feeling really positive. I have been in the job now for just over five weeks, and [then] we were at only 14 per cent in the opinion polls and were seen as being on the sidelines - not on the pitch at all.
“In that five-week period I think we have managed to establish ourselves. I think we have managed to get cut-through in terms of our message.”
He added: “I think that's showing insofar in the approval ratings, but what I say directly to people is if you like what I'm saying; if you think we can do things differently; if you believe we need to focus on recovery then you need to vote Labour in this election.”
Mr Sarwar said he saw “good progress signs” in the polls, but admitted: “I want us to do more progress in the next four-and-a-bit weeks.
“If you think we shouldn't go back to the old arguments, but you want our Parliament to focus on you, your family, and our national recovery, vote Labour on May 6.”