Replacing the billboards has been a costly exercise.
"We're left with sheets of plywood, while other candidates have their personalised billboards."
Having security cameras would be one way to deal with the vandals, Mr Borrows said.
"It's a pretty pathetic response and it's hugely frustrating because we have to go and buy new ones."
Pacific Helmet chief executive and former National Party regional chairman David Bennett has complained about the vandalism to police.
"It's unusually prolific for this particular level of vandalism," Mr Bennett said.
Any information about the attacks would be appreciated, he added. "I understand the party is considering offering a reward for information that leads to those responsible." Whanganui Labour candidate Hamish McDouall said any suggestion the Labour Party was involved was "ridiculous".
"I made it very clear we're not doing it. I did notice the other day both mine and Adrian Rurawhe's signs were knocked down - it happens to all parties."
Mr McDouall said "gutter suggestions" that the Opposition was responsible only distracted from the larger issues facing the National Government.
"The fact is there has been damage, but there's a lot of anger at what the Government has done - I'd much rather people just vote the National Party out."
John Boynton is an AUT journalism student on work experience at the Chronicle