Try onclick function separately it can give you access to execute your function which can be used to open up a new window, for this purpose you first need to create a javascript function there you can define it and in your anchor tag you just need to call your function.

Example:

function newwin() {              
 myWindow=window.open('lead_data.php?leadid=1','myWin','width=400,height=650')
}

See how to call it from your anchor tag

<a onclick='newwin()'>Anchor</a>

Update

Visit this jsbin