Through most of the past year, the two main questions about the Republican nomination campaign were who would emerge as the most viable challenger to Mitt Romney and whether Republicans could learn to love the former Massachusetts governor. With the results from Iowa’s caucuses now tallied, those questions still have no answers.

The close finish here among Romney, former senator Rick Santorum (Pa.) and Rep. Ron Paul (Tex.) could be a blessing for the former governor. Although Santorum and Paul proved the doubters wrong with their strong showings Tuesday, neither appears to have the capability yet to go the distance in a long nomination contest.

The candidates who many GOP strategists once believed might be able to give Romney a run — Texas Gov. Rick Perry and former House speaker Newt Gingrich (Ga.) — badly trailed the leaders. Romney advisers have been saying privately over the past few days that any outcome putting Gingrich and Perry in the lower half of the field would be ideal, no matter the order of finish among the top three.

But Romney’s lackluster percentage underscored the absence of enthusiasm among many Republicans for the candidate long seen as the party’s likeliest nominee. Despite being the nominal front-runner for the past year and judged overwhelmingly by Iowa Republicans as having the best chance of defeating President Obama in November, Romney did no better Tuesday than he did four years ago.

The results did little to damage Romney’s prospects of winning the nomination, though. He is well-funded, and he has a strong campaign team, a sharp focus on Obama and the economy, and a willingness to go after anyone he sees as a threat.

Gingrich and Perry both felt the power of his political machinery. Santorum, if he is judged to be a true threat, will soon feel it too, whether from Romney’s campaign directly or from the “super PAC” that is backing his candidacy and that poured millions into attacks against Gingrich.

Santorum’s showing in Iowa was impressive, but it is important to note that he managed to avoid being attacked by any of his rivals, which will not be the case going forward.

Romney will arrive in New Hampshire on Wednesday morning as the prohibitive favorite to win its primary next Tuesday. If he can come close to the margin he has enjoyed in the most recent polls there, he will have a clean victory. But because presidential candidates from Massachusetts are expected to do well in the Granite State, the value of a Romney victory would be limited.

Instead, the next real battleground will be South Carolina, whose Jan. 21 primary now shapes up as a major test for all the candidates, followed by Florida on Jan. 31. Romney did poorly in South Carolina four years ago and, in a state with a reputation for rough-and-tumble Republican politics, his rivals will be lying in wait for him.

Santorum can claim that he is the conservative alternative to Romney, given that his under-funded and hugely underestimated campaign surprised nearly everyone on Tuesday. He closed out his campaign in Iowa by asking voters to ignore the political pundits who said he had no chance and to do what Iowans have long done — be the first to tell the rest of the country what to think about presidential candidates.

Santorum’s best hope in South Carolina is for the other candidates to fade quickly, leaving him a clear opportunity to take on Romney directly. A crowded field in that state dividing up the most conservative portion of the electorate would only be another bit of good luck for Romney.

Paul doubled his strength in Iowa, compared with four years ago, with a tea party message of shrinking government and radically cutting spending. Some Republican leaders call him a fringe candidate, but he is now a force that the party may not be able to ignore. Though he espouses views outside the GOP mainstream on foreign policy and some domestic issues, he showed the power of that message Tuesday by bringing independents into the caucuses and demonstrating strong support from young voters.

Paul’s strength among independents in Iowa raises a cautionary flag for Romney in New Hampshire, where independents often play a more significant role than in Iowa. A surge of independents for Paul could hold down Romney’s margin and make his expected victory look less handsome.

Santorum, too, has vowed to campaign hard in New Hampshire. He has spent considerable time there, as he did in Iowa. His diligence paid huge dividends on Tuesday, but he will need all the help he can get to translate that into a strong showing against Romney a week from now.

New Hampshire also will be decisive for former Utah governor Jon Huntsman Jr., who skipped Iowa to concentrate his efforts there. He also is counting on independent voters, though perhaps not of the same philosophical views as Paul’s libertarian followers.

Iowa’s role in past campaigns has not been to project the eventual nominee. Instead, the Hawkeye State has helped to winnow the field. But Tuesday’s results provide an incentive to most of the candidates to keep going.

The top three finishers can claim one form of victory or another, but even two of those who placed out of the money — Gingrich and Perry — could find reasons to keep their hopes alive. Gingrich said he will keep going, but Perry said in his concession speech that he will return to Texas to reassess his candidacy.

“With the voters’ decision tonight, I’ve decided to return to Texas, assess the results of tonight’s caucus, determine whether there is a path forward for myself in this race,” he said.

Rep. Michele Bachmann (Minn.), who won the Iowa straw poll in August but was in single digits Tuesday, may also have to rethink the viability of her candidacy.

Even before Iowa’s results were tabulated Tuesday night, the state of play in the next three states to vote was anything but clear. Romney has held a strong and steady lead in New Hampshire, which his campaign has long seen as his place to rebound from any disappointment in Iowa. Paul has been running second there.

South Carolina has held the decisive primary in Republican presidential races dating back three decades, but the terrain there is likely to change quickly on the basis of Iowa’s results. The most recent polls put Gingrich at the top of the field, followed by Romney. But those polls were taken before the former speaker began to plummet nationally.

Romney has looked stronger in South Carolina in this campaign, but the state still presents a serious challenge, particularly if one candidate begins to consolidate the conservative vote there.

Meanwhile, Romney’s campaign began airing a television ad Tuesday in Florida. It was a sign of both the significance his team places on the Sunshine State and its determination to use its resources to gain an early edge on whoever Romney’s principal challenger is by the primary at the end of the month.

Whether the nomination contest will end quickly or drag on was unanswered by Iowa. Romney’s advisers clearly believe they are in a strong position now to win. But questions about their candidate’s ability to rally the party will be left to voters in other states to answer.