By all means, let's talk about how best to create opportunity.

For some time now, groups on the left have been pushing Democrats and the White House to pick a big fight with Republicans over the fact that student loan interest rates are set to double when a federal law expires this summer. The White House is now set to join the battle:

President Obama begins an all-out push on Friday to get Congress to extend the low interest rate on federal student loans, White House officials said, an effort that is likely to become a heated battle along party lines. If Congress fails to act, the interest rate on the loans, which are taken out by nearly eight million students each year, will double on July 1, to 6.8 percent.

White House officials said the president was planning a sustained effort through the spring....on Saturday in his weekly address, the president will call on Congress to pass legislation preventing the rate hike.

Next week, Mr. Obama will again hammer the issue — during visits on Tuesday to the University of North Carolina at Chapel Hill and the University of Colorado at Boulder, and on Wednesday at the University of Iowa.

Republicans have argued that the extension heaps great costs on the backs of taxpayers. But a Dem points out that the cost of a one-year extension — $6 billion — is only marginally more than the annual amount that the Buffett Rule would have brought in, which Republicans argued was laughably trivial.

There’s already an infrastructure on the left that’s primed for this fight. The group CREDO Action has been organizing on the issue and urging Dems to take it on; it has collected 230,000 signatures.

But CREDO may not be satisfied if the Obama administration pushes for only a one-year extension. The group is set to go out with an email to supporters asking them to pressure Dems not to compromise on any one-year measure (presuming Republicans are even willing to do that).

“If we build massive support, we can prevent an early compromise that would put off the doubling of the interest rates for only one year — a compromise that is both unnecessary and not nearly good enough,” the email says.

That aside, the battle over student loans serves a good political purpose for Dems: It feeds into the argument between the parties over how best to create opportunity, a dispute that is central to the presidential race. Republicans and Mitt Romney argue that Obama's call for action to combat inequality is class warfare and insist the best way to reduce it is to sweep away government, unshackle the private sector and allow it to create opportunity for everyone. Obama and Dems counter that Republicans don’t really favor any genuine effort to create opportunity and that government action is necessary to increase social mobility, and with it, shared prosperity— via funding education, for instance.

The battle over extending student loans takes this argument out of the realm of the abstract, and places the debate over whether government should act to facilitate opportunity before the voters in concrete terms.