Mayor David Miller and Toronto's environmental community are using Earth Day to continue their lobbying push for full funding of Transit City.

"In 2007 on June 15, when the premier (Dalton McGuinty) announced it, he said the time is now," Miller said Thursday at a news conference.

Three years later, construction has started on one line for Transit City, which when finished will provide a 120-kilometre network of light-rail transit across Toronto.

"There's no reason we can't go ahead on the others. We simply need the provincial government to say, 'Go ahead.'"

He then signed the Transit City support pledge.

Miller said among other things, the LRT network will link neighbourhoods that are currently isolated to the rest of the city.

On Thursday afternoon, Miller is to be at Yonge Street and Eglinton Avenue with Coun. Karen Stintz, normally an opponent of the mayor on many issues. The two will be urging citizens to sign a petition urging full funding for Transit City.

In the March 25 provincial budget, the Liberal government said about $4 billion in capital expenditures for Transit City would be deferred as the province tries to wrestle down a $21.7-billion deficit.

The province has insisted the entire project will eventually be built, but some fear today's deferral is tomorrow's cancellation.

"They haven't said when they will flow with the ultimate dollars," TTC chair Adam Giambrone told reporters.

On Wednesday night, the Toronto Environmental Alliance held a rally in support of Transit City in city council's chambers.

"The four billion dollars -- We're going to save that money in gridlock we're going to reduce. There's going to be less hospital admissions because we're going to reduce smog with Transit City," said campaigner James Kilpatrick.

"So it's a really short-term investment that's going to make our city great in the long term."

One demonstrator said it took him five buses to get to his classes at Seneca College.

Besides signing the pledge, the alliance urged people to call Premier McGuinty's office to urge funding for Transit City.

With a report from CTV Toronto's Michelle Dube