Securing Login Page

If I setup my new wordpress blog website to be on a http website, not https, is there a way to have the login page be forced to use the secure page with https on it?

Also, if I want to make the home page not secure, but login pages all be secure, would it be best to just make the whole site use the secure pages?
Because if they login with the secure page, will the login be carried to unsecure pages then back onto the secure pages? or will them leaving the secure pages to the unsecure ones, delete their login and force them to login again?