Gordon Brown sought to portray Labour as the party of manufacturing as he unveiled a new manifesto for economic growth.
The Prime Minister said Labour would back research and investment by firms as part of a new "industrial activism".
He announced that an extension on tax relief on investments of up to £100,000 would remain for the whole of the next parliament under Labour.
Speaking at BMW's Mini plant in Oxford, Mr Brown restated his claims that the Tories would put the country's economic growth at risk.
"We have been fighting for the future of our economy, a future where we can come out of the recession and have strong growth," he told staff after a tour of the production line. And I don't want anything to happen that puts that recovery at risk.
"We are fighting for growth, we are fighting for jobs, we are fighting for apprenticeships, we are fighting for the skills of the future and I will continue to keep fighting."
Announcing that the doubling of the Annual Investment Allowance to £100,000 in the Budget would remain for the next parliament, he said: "We believe in supporting firms that invest in the economy for the future."
The Prime Minister travelled to Oxford with Business Secretary Lord Mandelson and Energy and Climate Change Secretary Ed Miliband.
Earlier, Nick Clegg said the Liberal Democrats are now the only party offering "real change" in the General Election. His claim stepped up the party's tussle with the Conservatives for ownership of the "change" mantle in the campaign for the May 6 poll.
Tory leader David Cameron sought to fight back against the Lib Dem surge in the polls on Monday night, with a hastily-rewritten election broadcast warning that only his party can deliver change and that a hung Parliament would leave Britain "stuck" with Gordon Brown.