LAURIE KELLMAN | August 31, 2012 08:49 AM EST |

WASHINGTON — Social Security. Medicare. Iraq. Afghanistan. Illegal immigration.

They’re all costly to taxpayers and the next president presumably will have to address them to one degree or another. Yet GOP presidential nominee Mitt Romney made no mention of those issues Thursday in his wide-ranging acceptance speech that closed the Republican National Convention.

The address was Romney’s most sweeping attempt yet to outline the case for his candidacy. It was no time to get into the nitty-gritty of federal budgeting and solutions to the nation’s ills. But Romney did find ways to talk about an array of other issues, some of them sensitive for him personally and politically.

Romney did, for example, pledge to “protect the sanctity of life,” a reference to abortion, even though there are clear differences on the issue between him and running mate Rep. Paul Ryan of Wisconsin. He referred to his family as Mormons, a rarity for a candidate who typically refers to his religion as “my faith.” And Romney even showed emotion, which he seldom does in public, when he spoke of longing to wake up again with a pile of children in the bedroom he shares with wife Ann.

But there was much Romney did not say, areas he didn’t address. And those unmentioned topics say a lot about the challenges that face the Republican ticket in the final three months of the presidential campaign.

Here are some examples and some clues about why Romney may have chosen to skip them:

_WHAT TO DO ABOUT WAR. Polls show that most Americans want to get American troops out of the costly wars in Iraq and Afghanistan, and President Barack Obama is generally seen as a president who is doing just that. Obama began drawing down the force with a plan to have all out by the end of 2014. While Romney has occasionally criticized Obama for signaling when the drawdown in Afghanistan would happen, he also has endorsed the 2014 end to U.S. combat in Afghanistan, subject to conditions at the time. Romney has criticized Obama’s withdrawal plan but offered few details about how he would change it.

_GOVERNMENT AID: On Social Security, Romney has not talked specifics about what we would do with these budget-busting entitlement programs other than to say he would gradually raise the retirement age on the massive program for aid to seniors. He generally has steered clear of proposals to touch Medicare and Social Security in the short run, which leaves a relatively limited portion of the $3.6 trillion federal budget to cut. His addition of Ryan has caused Romney a headache as Democrats seek to make him own Ryan’s budget proposals that call for Social Security benefits based on workers’ needs and optional private alternatives to Medicare.

_ILLEGAL IMMIGRATION: It’s a touchy subject for both Romney and the Republican Party. Challenged on the right during the primary season, Romney struck a tougher stance on the issue than he had in the past. He emphasized his support for a U.S.-Mexico border fence and his opposition to education benefits to illegal immigrants, sometimes in sharp tones that caused some Hispanics to turn away. That’s potentially problematic because Republicans are trying to narrow the advantage Democrats have among Hispanics, the nation’s fastest-growing ethnic minority group. It represents large chunks of the voters in swing states like Florida and Colorado. Some 12.2 million Hispanics are expected to vote in November.

While Romney glossed over these issues, it’s a good bet Democrats won’t let him do so again between now and November.