Ferrari team boss Jean Todt has warned Formula One's governing body that some teams are likely to oppose its radical plans to overhaul the sport. A meeting between the teams and F1 bosses Max Mosley and Bernie Ecclestone last week debated changes aimed at cutting costs and improving the show.
But Mosley needs the the teams' backing to make changes before 2008.
"You can only change something if you have unanimous team agreement, and I'm not sure it will be easy," Todt said.
Todt's Ferrari team claimed another one-two finish in Sunday's Spanish Grand Prix to increase fears that they could dominate the year like they did in 2002, when they won 15 of the 17 races. At the end of that season, the FIA introduced major rule changes in an effort to re-ignite fading interest in the sport.
The latest raft of proposals, which include a new engine format and a ban on electronic driver aids, are virtually set firm for 2008, when the existing Concorde Agreement that governs the sport ends.
 | I'm convinced the majority will be in favour of some new directions, but that's not enough  |
But the teams are in talks about bringing in some of the changes earlier than that, with cost-cutting their major aim.
But Ferrari have the biggest budget in F1 and Todt indicated that he would not be rail-roaded into accepting the changes.
"You need to analyse each single thing very carefully and to bear in mind that the first intention of what we agreed is to reduce cost and to improve the show," said Todt.
"We must make sure that changes make it go in this direction, because otherwise you don't achieve what you want.
"I'm convinced the majority will be in favour of some new directions, but that's not enough."