National is upping the tempo on the pre-election campaign, erecting billboards designed to throw into stark relief the difference between a Government led by Helen Clark and one led by Don Brash.

It began nailing them up across the country yesterday, including one relating to the Foreshore and Seabed Act which is likely to provoke controversy.

The red and blue billboards contrast a grumpy-looking Helen Clark with a smiling Dr Brash and canvass key themes from tax to race relations.

The design of the eight different billboards emulates that of earlier ones erected on roading and education, with similarly short slogans.

The party believes some of its messages during the last campaign were overly complicated and lost voters' attention.

Its message is that National will deliver to "mainstream" New Zealanders, who it claims Labour has ignored.

On "violent criminals" under Labour they are "out in no time" while under National they would "do the whole time".

Under the question "which school?" National would let "you decide", while under Labour "we decide".

But it is what some will perceive as the black and white nature of the race relations billboard that National campaign manager Steven Joyce acknowledges may "possibly" spark a backlash.

Under the heading "Beaches" are the words "iwi" on the Labour side and "Kiwi" on the National one.

Mr Joyce maintained the message was more subtle than it might appear and "with the iwi being part of the word Kiwi as well" was not setting up an iwi vs kiwi polemic.

"On the one hand the focus is on the guardianship of the beaches for iwi and the other is the focus of all Kiwis and obviously that includes iwi and that's part of the message of the billboard."

Mr Joyce said the billboards were paid for out of the party's campaign fund, so taxpayers had not coughed up for them. He wouldn't say who designed them.

"We're keeping that to ourselves. There's a small team of contractors that we are working with this time who we haven't used before."

The billboards marked another stage in the election campaign, he said.

"Labour is still not deciding when the election is going to be and they're playing this game with us. But our feeling is that its time to up the tempo a bit."