The Australian Democrats have dumped their candidate for the Adelaide seat of Sturt after it was revealed he had a conviction for trying to procure a child for sex.

The party says Darren Andrews has gone to ground and has not contacted them, while his posters were taken down last night.

Channel 7 News revealed the details of Mr Andrews' conviction, in which he had tried to meet a 15-year-old boy who turned out to be a police officer posing as a child on the internet.

Mr Andrews is a journalism student at the University of South Australia and a recipient of the Pride of Australia Award.

The Democrats' lead Senate candidate Jeanie Walker says Mr Andrews lied to the party about not having a criminal record.

"Unfortunately the party found out when the media contacted us, so we've only just known basically just before it went to air on Channel 7," she said.

"We've started pulling down the posters and ceasing campaigning in Sturt as soon as we were contacted by the media.

"Obviously we're all very shocked, but I believe that common sense will prevail and the people will realise that there was no way for us to foresee this happening."

Ms Walker says the party will be enforcing compulsory police checks on all potential candidates.

"That was actually discussed in our national executive a couple of months ago, but because the election was called so quickly that went by the wayside and didn't end up happening," she said.

"But that will definitely be coming out in the next few weeks - we'll be bringing out our policy and our program on how we will be doing that."

Ms Walker has defended the party's protocols.

"He at least did admit that he's lied to the party and to the AEC and the Australian Democrats had no way of knowing anything about this," she said.

"We obviously didn't believe there was any reason that we should've been digging into his past and trying to find out anything, there was no reason to suspect any problems."