* Johnson offers Brexit 'Christmas gift'
* Conservatives say will not to raise taxes
* Labour leader to be neutral in second Brexit vote (Adds Johnson comments)
TELFORD, England, Nov 24 (Reuters) - British Prime Minister Boris Johnson promised on Sunday "to get Brexit done", pledging in his Conservative Party's manifesto to bring his deal to leave the European Union back to parliament before Christmas and ruling out any more delay.
With less than three weeks before Britain heads to the polls on Dec. 12, the governing Conservatives and opposition Labour Party are trying to tempt voters with different visions of the country's future, but both pledging to spend more.
Johnson's manifesto aims at drawing a distinction with Labour, which has promised to raise taxes on the rich and businesses to fund a big expansion of the state, by promising not to increase taxes if the Conservatives win the election.
Opinion polls show Johnson's Conservative Party commands a sizeable lead over the Labour Party, although large numbers of undecided voters mean the outcome is not certain.
"Get Brexit done and we shall see a pent up tidal wave of investment into this country," Johnson said, launching his manifesto in at a conference centre in Telford in central England.
"Get Brexit done and we can focus our hearts and our minds on the priorities of the British people."
Arriving at the centre, Johnson was welcomed by supporters chanting "Boris" but a little further away, protesters shouted: "Liar, liar, pants on fire".
Contrasting with Labour's unabashed tax-and-spend approach, Johnson's manifesto - titled "Get Brexit Done, Unleash Britain's Potential" - will pledge to freeze income tax, value-added sales tax and social security payments.
Johnson will announced 3 billion pounds ($3.85 billion) for a National Skills Fund to retrain workers and an extra 2 billion pounds to fill pot-holes in roads. He will also pledge to maintain the regulatory cap on energy bills.
Labour spokesman Andrew Gwynne said Johnson's plans were "pathetic". "This is a no hope manifesto, from a party that has nothing to offer the country, after spending 10 years cutting our public services," Gwynne said.
To try to win over voters, Labour announced another spending commitment, promising to compensate more than three million women who lost years of state pension payments when their retirement age was raised.
Think-tanks such as the Institute for Fiscal Studies have raised questions about the credibility of plans to fund investment from both the Conservatives and Labour.
Held after three years of negotiations to leave the European Union, the December election for the first time will show how far Brexit has torn traditional political allegiances apart and will test an electorate increasingly tired of voting.
In a heated campaign where the Conservatives have been criticised for disseminating misleading social media posts, Johnson, 55, will say he will "turn the page from the dither, delay and division" of recent years.
Labour has said it will negotiate a better Brexit deal with the EU within six months that it will put to the people in a new referendum - one which will also offer the choice of remaining in the bloc.
Corbyn has said he would remain neutral in such a vote, something his finance policy chief John McDonnell described as the Labour leader adopting the role of "an honest broker".
Johnson criticised the stance.
"They want to rip up our deal and negotiate a new one. But we don't yet know of a single Labour MP (member of parliament) or any other MP who would support this deal," Johnson said to applause and laughter.
"It would be farcical, it would be comical if the consequences of that approach were not so disastrous for this country and our prospects next year. Let's give that madness a miss." (Additional reporting by Elizabeth Piper, Kate Holton, Bill Schomberg and Andy Bruce, Editing by Chizu Nomiyama, Emelia Sithole-Matarise and David Clarke)