Victorian Premier Daniel Andrews will be a key weapon for Labor in May's federal election, as the state emerges as a major battleground in the campaign.

Labor believes it can take up to five Victorian seats from the Liberals in May’s election – enough to win government – using the momentum of Mr Andrews' triumph in November’s state election.

In an early taste of Labor's campaign strategy, federal leader Bill Shorten appeared with the Premier and fellow party heavyweights Anthony Albanese and Mark Dreyfus in outer Melbourne on Sunday, promising $850 million in new funding for congested roads in the city's outer south-east.

Labor's move, stepping up its infrastructure fight against the Coalition in Victoria, came as the Liberals continued to celebrate their victory on Saturday night in the NSW state election.

But a poor performance for the Nationals in Saturday's poll suggests there may be pain in store for the junior Coalition partner when the nation votes in May.