Closing his party's conference he said the Lib Dems are the only party capable of depriving the Tories of a majority at the next election.
In a keynote party conference address, Mr Farron made a pitch to attract Labour moderates unhappy with Jeremy Corbyn's leadership as he heaped praise on the controversial former prime minister.
Baroness Sal Brinton, president of the party and Christian, told Premier's News Hour: "We are coming back because we have progressed. We were well below five per cent this time last year, things look awful, but that was after a really extraordinary general election.
"We used to be on an average of about 15 to 18 per cent and I don't think we're far off that now.
"We are definitely back from having fallen over a cliff and that means that Tim Farron is leading a party that is in good hope and absolutely determined to do what it can to help the country."
The Lib Dem leader insisted he would not be put off because the party had been "crushed" after being in coalition and reduced to just eight MPs, because he is a "great loser" capable of bouncing back after the Brexit referendum defeat.
Farron also insisted the Lib Dems are ready to raise taxes to save the NHS and determined to reverse the rush to Brexit.
Baroness Brinton agreed the pledge to raises taxes for the NHS was "bold" but added: "We are absolutely clear that the NHS is on its knees and needs investment.
"Every single hospital trust is running a deficit at the moment, people are having operations delayed and the population is growing older which means actually our hospitals and our doctors are going to be busier.
"We believe it's right to pay a little more income tax in order to make sure that our wonderful NHS can continue to function".
Baroness Sal Brinton speaking to Premier's Antony Bushfield: