TAMPA, Fla. — Four years ago, a previously unknown Alaska governor surprised and electrified a Republican convention that was yearning for something to get excited about as a historic November defeat loomed.

This time around, the GOP knew what it was getting in Paul Ryan, the party’s 2012 vice presidential nominee — and it was already excited about him. But the unanswered question was whether this relatively young, 42-year-old Wisconsinite making his debut on the national stage would project the aura of a president and instill the kind of confidence among independents, undecided swing voters and soft partisans to boost Mitt Romney’s case against President Barack Obama.

The main event for Romney (and the most important speech of his political career, so far) is still tonight, when he will formally accept the Republican presidential nomination. But Wednesday evening was important for the former Massachusetts governor nonetheless, as Ryan’s performance would either validate or cast doubt on his first major presidential decision.

The House Budget chairman didn’t deliver the stem-winder that Sarah Palin served up to convention delegates in St. Paul, Minn., in 2008. But in the professorial, plain-language tone that has been the hallmark of his speeches on the House floor and at think tanks across Washington, D.C., for years as he pushed his sometimes-controversial fiscal reforms, he dissected Obama’s record with humor and precision — and in a way that might appeal to the geographic and demographic voting blocs Romney needs to beat Obama.

Additionally, Ryan offered one of the most compelling cases for electing Romney that had yet been delivered on the convention floor (or for that matter, on the campaign trail) save for Tuesday evening’s speech by Ann Romney. Ryan’s praise of Romney appeared heartfelt, as opposed to the usual campaign boilerplate that is required of the running mate — and it was believable because it fit with who Romney is as a person as opposed to who some GOP strategists wish he was. Besides acknowledging, to laughter, that Romney’s choice of music was from a different generation, he also tackled more substantive issues about Romney the man.

“Mitt and I also go to different churches.  But in any church, the best kind of preaching is done by example.  And I’ve been watching that example,” Ryan said. “The man who will accept your nomination tomorrow is prayerful and faithful and honorable. Not only a defender of marriage, he offers an example of marriage at its best. Not only a fine businessman, he’s a fine man, worthy of leading this optimistic and good-hearted country.”

Ryan took the podium to a raucous convention welcome, but he appeared a bit flat as he opened his remarks. However, the Congressman only improved from there, and by the time he was well into the second half of his address, he was connecting with the crowd and filling out the stage with a presence befitting of a potential commander in chief. Ryan was energized, paused for effect and applause at all the right moments and showed why he has won re-election over and over in a district that is far less conservative than he is.

Romney hired Ryan to help him make an effective case against Obama and for Republican governance and a GOP White House. On Wednesday night, Ryan did his job. Will Romney do his?