New voter enrolments or updating the current electoral database will likely impact negatively on Coalition support, a new study said, potentially shaving off marginal numbers from the opposition and swinging them over either to the government or the Australian Greens, reports said.

In a report by Professor Ian McAllister of the Australian National University, the Coalition's primary votes would slide to 38.8 per cent from 40.3 per cent if at least another 1.5 million voters will be added the to the national electoral database.

This projection was based on earlier action by the Parliament, which in June 2012 gave its go signal for the Australian Electoral Commission to update voters' particulars and possibly enlist new and young voters by the mid-part of 2013.

The commission will be aided by the appropriate government documents for the undertaking and should that push through, the opposition's electoral stature will not be as rosy as it is today, Prof McAllister said, adding that the assumption was based on four Newspoll surveys that involved 4,857 voting-age Aussies.

The professor clarified, however, that the forecast Coalition slips are "small changes, but they would be magnified in inner city areas where young people are more concentrated."

But he told The Australian on Monday that "they could easily affect the outcome in a tightly held seat. The result in around half a dozen seats could be determined by these enrolment changes."

In an interview with the Australian Associated Press (AAP), Nielsen pollster John Stirton concurred that with the new electoral laws in place, the Coalition may find itself struggling because "young people are slightly less likely to be enrolled to vote and are more likely to vote for Labor and the Greens."

But he noted that the "the numbers would be quite small . . . we're only talking at the margins."

These are the areas where the Coalition holds an average of about two per cent, The Australian said, which include Boothby in South Australia (0.3 per cent); Hasluck in Western Australia (0.6 per cent); and Aston in Victoria (0.7 per cent); Brisbane (1.1 per cent) and Solomon in Darwin (1.8 per cent); Herbert in far north Queensland (2.1 per cent) and Swan in Perth (2.5 per cent).

In the aftermath of direct enrolment on July 2013, it is the Greens which will benefit the most, Prof McAllister said, as the party is slated to see an uptick in primary vote of 11.5 per cent from 10.9 per cent.

Labor's primary, on the other hand, will hop by a full percentage point to 34.9 per cent, the professor added.

These changes, however, are representative of Labor's "rorting of the roll," senior Liberal frontbencher Christopher Pyne said on Monday.

This latest iteration, Mr Pyne said, is Labor's routine manner of scoring it big over the Liberals.

But Treasurer Wayne Swan dismissed the Coalition claims as simply cynical.

"(Mr Pyne) is just interested in trying to exclude people from the electoral roll and you would have to ask him why that's his objective," Mr Swan said.