OLYMPIA, Wash. — Political leaders in Olympia are considering an overhaul of the state's popular initiative system, proposing a requirement that ballot measures have their own funding source. A group of lawmakers proposed a constitutional amendment Thursday. The Legislature and Gov. Chris Gregoire have expressed frustration with voter-approved measures that require hundreds of millions of dollars in spending with no way to pay the bill. Senate Republican Leader Mike Hewitt says voters need to understand the consequences of the initiatives. Gregoire says she would probably support such a constitutional amendment, saying the public needs to be responsible for finding the money as the Legislature would be. Voters last month gave overwhelming approval to an expansion of training for long-term care workers. The measure costs about $18 million over the next two years and has no funding source.