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 -- quote -- "Mitt's Choice for VP is Paul Ryan."

Romney and Ryan are kicking off a four-day bus tour that will take them to as many states.

At 42, Ryan is a generation younger than the 65-year-old Romney.

Congressman Paul Ryan of Wisconsin is chairman of the House Budget Committee, and primary author of conservative budget plan that would remake Medicare and cut trillions in federal spending. The Republican-controlled Congress passed Ryan's tax and spending blueprints over vociferous Democratic opposition in 2011 and again in 2012.

In a written statement, Romney's campaign says Ryan has worked in Congress to "eliminate the federal deficit, reform the tax code and preserve entitlements for future generations."

Appearing Saturday for the first time as Mitt Romney's running mate, Wisconsin Rep. Paul Ryan attacked President Barack Obama for what he calls a "record of failure."

The seven-term congressman says Obama has led the "worst economic recovery in 70 years." He notes that unemployment has been above 8 percent for more than three years — the longest stretch since the Great Depression.

He spoke in remarks prepared for delivery at the first public appearance of the new GOP ticket.

Ryan, the architect of a controversial budget plan, is promising not to "duck the tough issues." And he says he has the courage to tell the truth.

Tags: president, Barack Obama, GOP, Mitt Romney, Paul Ryan