Green councillors can have "a big impact", even if they are not running the council, according to the party's co-leader.
Carla Denyer was campaigning in Dartford ahead of the Kent County Council (KCC) election on Thursday.
The Green Party has five KCC councillors but hopes to make some gains.
Denyer told BBC South East that it was worth voting Green, even though they were unlikely to win a majority.
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She said: "Even where Greens aren't in administration, having a few Greens in the room often helps to change the conversation by putting questions and fresh perspectives on the agenda.
"We've seen that having a group of green councillors, even if they're opposition, can have a big impact on the decisions that councils make by holding the administration to account by asking the questions that nobody else is asking and by putting that political pressure on to, for example, protect local services."
To win a majority on KCC, which has been Conservative-run since 1997, 41 seats are needed.
Denyer said the party was open to collaborating with other parties in order to form a coalition if a single party did not secure a majority, but ruled out working with Reform UK.
Clean air zones
One particularly controversial issue in Dartford has been the expansion of London's Ultra Low Emission Zone (Ulez).
In August 2023, it was expanded to all London boroughs, up to the border of Dartford, in an attempt to tackle London's air pollution.
Some residents expressed frustration that those with non-compliant cars would need to pay £12.50 every day that they crossed the border into London.
Speaking in Dartford, Denyer said her party supported the principle of tackling air pollution, but any similar schemes for Kent would be a matter for her colleagues in the local party.
The Bristol Central MP added: "Thousands of people in this country die prematurely every year because of the air pollution in our towns and cities and overwhelmingly that affects the lower income families who are more likely to live in more polluted areas.
"Clean air zones can be part of the solution but it has to be alongside providing better public transport services."
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