convert any date into dateTimestamp in order to compare it

I’m trying to compare the current date timestamp with product special price end date.
to get current date I use :

$currentDate = Mage::getModel('core/date')->timestamp(time());

and for specialToDate :

$promoEndDate = strtotime($product->getSpecialToDate() );

the problem is that magento changes the date format when someone changes the admin locale and then strtotime for promo price returns null.
does anyone have an idea how can I retrieve getSpecialToDate() and convert it to timestamp ?

Thank you :))