Another week, another car talk. Barack Obama stopped by a North Carolina truck factory on Wednesday to announce $1bn in tax credits and grants for alternative-energy cars and trucks. It was Obama's third speech on cars and fuel in an election battleground state in three weeks.

The president has travelled from New Hampshire to Florida and now North Carolina to insulate himself from Republican attacks on rising gas prices and the on-again, off-again Keystone XL tar sand pipeline ahead of the general election.

"We can't just keep on relying on the old ways of doing business. We can't just rely on fossil fuels from the last century. We've got to continually develop new sources of energy," Obama said in his speech at the Daimler truck plant in Mount Holly North Carolina.

The White House, briefing reporters on the plane and through a factsheet emailed out before the event, said Obama's factory tour was intended to spur the development of a new generation of clean, fuel-neutral cars: electric, natural gas, and alternative fuels.

The Daimler plant is working to produce 18-wheeler trucks that use only half as much gas as current models. Long-haul trucks make up just 4% of all vehicles on the roads, according to the White House, but suck up 20% of all transport fuel in the country.

The factory also makes hydrogen-powered trucks.

The tax credits – which must be voted on by Congress – would help up to 15 cities and towns to pay for charging stations for electric cars and biofuel pumps for alternative fuel vehicles to encourage people to switch to electric cars.

"At the end of the day, it doesn't matter how much natural gas, or flex-fuel or electric vehicles you have if there's no place to charge them up or fill them up," Obama said.

The speech came just a few days after GM announced a five-week hiatus in the production of its Chevy Volt because of flagging demand.

Obama is also asking Congress to expand the tax credit for advanced vehicles to $10,000 from $7,500, and to all fuels – including natural gas, which is not covered under the programme.

It's unclear whether either programme will see the light of day, given Republicans' dominance in Congress and their opposition to Obama's clean energy agenda.

The Republicans claim clean energy loans and grants are a waste of money – and have used the failure of the Solyndra solar power maker to try to discredit Obama's energy agenda.

Earlier on Wednesday, the Senate minority leader, Mitch McConnell, told reporters Obama was bent on forcing up gas prices.

"When it comes to the rising cost of gas at the pump, it's my view that the administration's policies are actually designed to bring about higher gas prices," he said.

But the White House – with its steady schedule of energy-focused events – is clearly positioning itself to tout its energy agenda at the election.

Obama also used his speech in North Carolina to repeat his call for the repeal of billions in subsidies for the fossil fuel industry.

Subsidies were the main topic of his speech in the swing state of New Hampshire last week.

The week before, Obama took on Republicans' attacks on gas prices in a speech in Miami. In late January, he visited the University of Michigan to talk up his electric vehicles programmes.

All three are seen as battleground states in the November elections – but North Carolina is probably the biggest stretch for Obama.

He was the first Democrat to win the state since Jimmy Carter in 1976. The Democrats are fighting hard to hang on, locating the party's convention in Charlotte, North Carolina this summer.