Republican presidential candidate Mitt Romney has selected Wisconsin Rep. Paul Ryan to be his running mate.
The candidate made his announcement to supporters via a phone app, saying "Mitt's Choice for VP is Paul Ryan."
The GOP ticket is kicking off a four-day bus tour today that will take them to as many battleground states.
At 42, Ryan is a generation younger than the 65-year-old Romney and the seven-term Wisconsin congressman is a favorite of some conservatives.
Ryan heads the House Budget Committee and is author of a House-passed budget that would slash federal spending and overhaul entitlement programs like Social Security and Medicare.
