Conservative chairman Theresa May has told the party they have to welcome all Britons for who they are, whether "rich or poor, straight or gay, black or white".
May: Poured scorn on Lib Dem ambitions to overtake the Tories
The Conservatives can win the next election but have to change the things holding back their ability to triumph, she said in her keynote speech at the Tory annual conference in Blackpool.
With talk of leadership plots overshadowing major policy announcements, she urged members to use the "most important conference we have held in a decade" to show they are united.
And in the wake of being pushed into third place in the Brent-East by-election, she poured scorn on Liberal Democrat ambitions to overtake the Tories, as well as attacking Tony Blair's "spin and deceit".
'Party of today'
Mrs May last year caught the headlines when she warned the Tories they were still seen as the "nasty party".
This year, she said: "As the eyes of Britain focus on us this week, let us show them the real Conservative Party.
"A party of hope and aspiration, of freedom and social justice, of fairness and opportunity. A united party - for everyone, and of everyone."
She said the party must be seen as a "party of today" if it is to become a 21st century government.
The Tories should take the fight to their opponents, she said, arguing that people were now starting to look for a new government.
"If we are going to build a party to win, we are going to have to challenge and change the things that old back our ability to win," she said.
She congratulated constituencies who had chosen black and Asian candidates, but said more progress was needed.
The party also had to use the most up-to-date techniques - such as e-mail and text messaging - as it geared up its campaigning ahead of the next election, Mrs May argued.
The Tories were the only party that could replace Labour, she said, but there was no such thing as a "natural party of government".
"So if we are to win, we will have to earn it," she continued. "People want an end to the sniping, the point scoring, the ranting and
raving that often passes for political debate in Britain today.
"They want a different kind of government. As Conservatives we should take
the lead. We should leave the yah-boo stuff to others and instead behave in a
way that gives credibility to our promises."
The Conservatives have stepped up their attacks on their Lib Dem rivals in the wake of the Brent East vote.
Mrs May insisted Charles Kennedy's party were not an alternative, saying the Lib Dems wanted to "give votes to convicted rapists but criminalise parents for smacking their children" and to "allow anyone to use any hard drug at home but to ban smoking in public".
She said the Monster Raving Loony Party had complained about the Tories calling the Lib Dems "loony".
But after seeing Lib Dem policies, had said: "I'm afraid that kind of nonsense would find no place in the Official Monster Raving Loony Party manifesto. We're loonies, not nutters."
She accused the Lib Dems of trying to be all things to all people but said it was not good enough just to shout them down at Westminster.
"We have to take them on ... on the fround and show them up for who they really are," she said.