A political advocacy group has spent more than $300,000 to air television commercials touting immigration reform legislation. The ads, which began airing last week, feature an up-and-coming senator stressing the need for the bill.

The organization paying for that message is not a liberal outfit seeking electoral advantage by adding Hispanics to the voting rolls.

It’s the American Action Network, which aims to “create, encourage and promote center-right policies based on the principles of freedom, limited government, American exceptionalism, and strong national security.”

And the senator starring in those spots is not a Democrat kowtowing to a special-interest group.

He’s Florida Republican Marco Rubio, one of the bipartisan “Gang of Eight” (including South Carolina’s Lindsey Graham), which has crafted a comprehensive proposal that grants some illegal immigrants a “pathway to citizenship” — but only after meeting stringent standards.

As Sen. Rubio puts it in the commercial:

“They’re going to have to wait 13 years. They’re going to have to pay fines. They’re going to have to learn English. They’re going to have to work. They’re going to have to wait at the back of the line.”

Yet some particularly hardheaded conservatives have condemned this bill as “amnesty” — just as they unfairly branded our senior senator “Lindsey Grahmnesty” when he dared to support similar immigration reform initiatives backed by Republican President George W. Bush during his second term.

Such demonization of conservatives seeking reasonable common ground on this issue persists — and threatens to scuttle the chances of immigration reform finally passing this year.

Sen. Rubio disputes a new Heritage Foundation report warning that the bill would impose high costs. He argues that the bill would pay for itself by creating millions of new taxpayers and other economic benefits.

And in an op-ed he wrote for The Wall Street Journal last week, Sen. Rubio offered this reassurance: “For those who have suggested that the border security triggers outlined in the Senate bill aren’t strong enough, we now have a chance to strengthen them.”

Of course, the border should be firmly verified as secure before we open the citizenship pathway to what is estimated to be at least 11 million illegal immigrants already in the U.S.

But the immigration-policy status quo obviously isn’t working. That’s why so many states, including this one, have enacted their own immigration laws.

Ultimately, though, illegal immigration is a national problem that demands a federal solution. And the immigration reform legislation from the Gang of Eight can provide a balanced answer to this challenge.

It also can serve the vital purpose of giving the authorities a better handle on who gets into the U.S. — and who is already here.

On April 21, six days after two terrorist bombs killed three people and injured more than 260 at the Boston Marathon, Sen. Graham pointed out on CNN’s “State of the Union”:

“What happened in Boston and international terrorism, I think, should urge us to act quicker, not slower, when it comes to getting the 11 million identified. I think now is the time to bring all the 11 million out of the shadows and find out who they are. Most of them are here to work, but we may find some terrorists in our midst who have been hiding in the shadows.”

Shining light on those shadows is a practical, overdue concept that conservatives should support.