The general election campaign is "crowding out" Thursday's local elections, according to the chief executive of the Welsh Local Government Association.
Steve Thomas warned there is a danger the council elections could become "a very large opinion poll" ahead of the Westminster vote.
Parties said they would be trying to make the difference between the two sets of polls clear to voters.
The local polls take place on 4 May.
Prime Minister Theresa May recently announced her decision to call a snap general election for 8 June, which is just over a month later.
Speaking to the BBC's Sunday Politics Wales programme, Mr Thomas said: "I think there is the danger with local elections as well that the local elections inevitably get crowded out by the national election.
"It's not surprising, there are huge issues at stake at a national level but that doesn't negate the importance of local elections.
"The local elections are about the services people generally care about: education, social care, their local environment - all those issues are massively important."
Asked if the increased coverage being given to the UK party leaders could influence the way people vote in the local elections, Mr Thomas said: "It could do, possibly, but when people stand in that polling station with that pencil in their hand, hopefully, they'll think about their locality and what they want to see happen in their locality over the next five years.
"Hopefully, people will turn out and they will make a commitment to voting in the local elections because, at the end of the day, this affects you as much as that national election."
Wales' Local Government Secretary, Labour's Mark Drakeford, said Theresa May's decision would have a "galvanising effect" on Labour supporters.
And the Welsh Conservatives' local government spokeswoman Janet Finch-Saunders said the extra political coverage was "energising politicians and the electorate" ahead of the local elections.
Plaid Cymru's local government spokeswoman Siân Gwenllian said the timing of the general election so close to the local elections was "a bit unfortunate".
While UKIP's Gareth Bennett suggested the general election could have been called a month later to "avoid some of this overlap".
Peter Black from the Liberal Democrats said: "It's my job as a local politician to go out there and persuade people that they have to vote for the right reasons in the right election."
Sunday Politics Wales, BBC One Wales, 11:00 GMT, Sunday 30 April