In Ken Cuccinelli II, 2016 hopefuls get a second warning.

A parade of Republican rising stars has streamed through Virginia in recent weeks, making last-minute campaign appearances with gubernatorial nominee Cuccinelli. Their goal is twofold: to drag Cuccinelli across the finish line and to field test their appeals to party activists who can, eventually, help them if they decide to run for president in 2016.

Sen. Rand Paul (R-Ky.) stumped with Cuccinelli in Virginia Beach. Wisconsin Gov. Scott Walker (R) hit several events in Northern Virginia on Saturday, where Republican activists sang to him for his birthday. And Sen. Marco Rubio (R-Fla.) will join Cuccinelli at two more events in Warrenton and Culpeper on Monday.

As those Republican all-stars urge party activists to get out the vote and counter the millions in advertising dollars Democrats have dumped into the race, some of the strategists who will eventually run their presidential bids are learning their own lessons from Cuccinelli’s campaign. For the second election cycle in a row, they fear, a prominent Republican has failed to seize control of the debate and allowed Democrats to define the parameters of the discussion.

To many Republicans, Cuccinelli’s campaign has resembled Mitt Romney’s run for president in 2012, a campaign that became as much about Romney’s record as head of Bain Capital as it was about President Obama’s first four years in office. Romney, who felt the need to tack right during the Republican primaries to fend off attacks from other members of his own party, stuck to many of the same lines he used during the primary, especially his criticism of the president’s health-care law. Cuccinelli, who has built his career as a culture warrior even as Virginia has evolved into a swing state, revels in his unabashed conservatism.

This year, Democratic nominee Terry McAuliffe and his allies have blasted Cuccinelli’s stands on abortion, contraception and other hot-button social issues. Cuccinelli has attacked McAuliffe’s business background, especially his management of the electric automobile company GreenTech. Both candidates have raised questions about each other’s ethics.

Observers say McAuliffe has succeeded in making the race about Cuccinelli; two-thirds of McAuliffe supporters in a recent Washington Post/Abt-SRBI pollsaid they were voting against the Republican, rather than for the Democrat. Cuccinelli has re-litigated the Affordable Care Act and focused on outside spending coming from New York City Mayor Michael Bloomberg and California environmental activist Tom Steyer.

“This is a referendum on Obamacare,” Cuccinelli said Saturday at a get-out-the-vote rally in Woodbridge. “Part of our momentum is the focus on Obamacare.”

The consequence: Polls show McAuliffe leading Cuccinelli, largely because the race is being fought on terrain favorable to McAuliffe.

The Washington Post/Abt-SRBI survey showed voters trusted McAuliffe and Cuccinelli about the same to handle transportation issues. When asked whom they trusted to handle taxes, energy and the economy, voters gave McAuliffe narrow edges. But when asked who they believed would better handle health care, abortion and issues of special concern to women, voters overwhelmingly picked the Democratic candidate. Much of McAuliffe’s television advertising has focused on those very issues where his advantage is greatest.

“As someone who has watched the election unfold on TV, I never got the sense that Cuccinelli told his story, at least not before he was defined by the McAuliffe campaign,” one Virginia-based Republican operative advising a potential 2016 candidate said in an e-mail. He was granted anonymity to candidly discuss the race. “Quick question: What’s Cuccinelli going to do if he’s governor? Answer: Um, not do deals with GreenTech?”

That rankles some Republicans, who say the key to winning Virginia is to focus on the economy, transportation and education. Gov. Bob McDonnell, another social conservative, made those issues the centerpiece to his successful 2009 campaign; “Bob’s for jobs,” read his yard signs that year. Another contrast is Walker, who won election in a traditional Democratic stronghold in part by maintaining a rigorous, disciplined focus on jobs and the economy.

On Saturday, Walker hinted at how he would present himself to Republican primary voters in 2016 as he drew parallels between his tumultuous first term, when he battled Democrats and union leaders and survived a recall election, and Cuccinelli’s campaign against McAuliffe.

“Who do you want in charge? You want those big government interests, those big union bosses at the table controlling what’s happening, or do you want the taxpayers in charge?” Walker asked about 150 Republican activists, more than a few of whom sported University of Wisconsin T-shirts. “This is someone who throughout his entire adult career has fought for the taxpayer,” Walker said of Cuccinelli.

Republicans caution against drawing sweeping conclusions about the health of the GOP from a low-turnout off-year race for governor in just one state. But they can draw lessons from the contrast between Virginia and the other gubernatorial race this year, in New Jersey, where Gov. Chris Christie — another potential 2016 candidate — is likely to cruise to re-election on Tuesday. Christie’s campaign has used most of the 16 television advertisements he has run this year to highlight his own record.

“There can be some healthy analyzing by Republicans on how some of the new nuts-and-bolts tactics they put in play performed, as well as the overall message and message discipline of the campaign and the candidate,” said Michael Biundo, the operative who ran former senator Rick Santorum’s insurgent presidential campaign in 2012. “Virginia is one of those purple states Republicans will need to win if we are going to take back the White House.”

If there is a lesson that presidential campaigns can learn from the two gubernatorial campaigns that conclude Tuesday, it is that seizing the initiative matters. Romney and Cuccinelli weren’t able to do that. Christie did.

Republican National Committee chairman Reince Priebus, eager to keep the focus on his party’s successes, will spend Election Day in New Jersey.