Can't drop .php extension from files in .htaccess

I'm trying to drop to .php extension on my files in the url. It seems like it should be really easy, but I can't get it to work.

For Example, If I link to a page in my site.

<a href="/admin_login.php">admin</a>

the url reads like this

www.domain.com/admin_login.php

I want it to read like this

http://www.domain.com/admin-login

In my .htaccess file I have this

RewriteEngine ON RewriteRule ^([^/.]+)$ $1.php [L] 

also tried this

RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME}\.php -f RewriteRule ^(.*)$ $1.php [R=301,L] 

What am I doing wrong?

Please don't tell me I have to go through my site and change every link to drop the .php extension.