Sen. Marco Rubio (R-Fla.) is set to deliver a speech on inequality on Wednesday. (J. Scott Applewhite/AP)

On Tuesday morning, Senate Republicans are expected to block an emergency measure to extend unemployment insurance. Soon after, President Obama will stand before a handful of the 1.3 million Americans who have begun to lose their benefits and try to shame Republicans for failing to help the nation’s neediest.

A similar political dynamic is likely to play out in the weeks and months to come as both parties battle to address mounting concerns over economic fairness and the growing gap between the rich and the poor.

Ahead of the 2014 midterm campaign season — and as the nation marks the 50th anniversary of President Lyndon B. Johnson’s “war on poverty” this week — Democrats and Republicans alike are trying to convince voters they are on the side of the middle class and those striving to break into it.

Although Tuesday’s initial Senate vote on unemployment insurance is likely to fail, some moderate Republicans said they were willing to continue negotiating for a potential deal to extend benefits in exchange for revisions to unemployment programs.

Next, Democrats plan to push to increase the federal minimum wage, part of an effort to make income inequality a core midterm campaign theme. Republicans are likely to resist an increase, but party leaders also face political pressure from vulnerable incumbents to demonstrate more compassion for the poor after back-to-back presidential election losses.

Who are the long-term unemployed?

For the GOP, the challenge is to move beyond the rhetoric of past campaigns and focus on specific policies showing the party would be effective on behalf of the poor. While some leading Republican figures are developing their own policy prescriptions in anticipation of the 2016 presidential race, there is little consensus within the party about a shared poverty agenda.

Sen. Marco Rubio (R-Fla.) will give a speech Wednesday that aides said will lay out changes to federal programs to help people climb out of poverty permanently. In the weeks to come, Rubio also plans to introduce ideas to make it easier for mid-career adults to go back to college or learn new job skills at vocational schools.

Rep. Paul Ryan (R-Wis.), the 2012 vice-presidential nominee, has been traveling to impoverished areas and meeting with community organizers. He plans to address poverty in an interview with NBC’s Brian Williams on Thursday.

A third potential GOP presidential candidate, Sen. Rand Paul (R-Ky.), is also putting a renewed emphasis on the poor, traveling to Detroit to pitch a plan to revitalize urban centers through “economic freedom zones.” Paul has given his message on income inequality an ideological edge — mixing lofty, empathetic language with anti-government broadsides.

House Majority Leader Eric Cantor (R-Va.), who has been visiting urban schools, will give a speech Wednesday promoting school choice as a way to address poverty. And Sen. Mike Lee (R-Utah) has proposed increasing the child tax credit as a means of blending social conservatism with anti-poverty policies.

Echoes of Jack Kemp

There is more intellectual energy around income mobility on the Republican side now than at any point since Jack Kemp, the late New York congressman, coordinated anti-poverty policy during George H.W. Bush’s administration in the early 1990s. Kemp, who advocated for public-housing reform and enterprise zones, mentored Ryan in the early 1990s, and he and Rubio regularly cite Kemp as their inspiration.

“On the outside, conservatives are talking about it more,” said Vin Weber, a former Minnesota congressman who co-founded Empower America, a free-market think tank, with Kemp. “But it’s nothing like it was with Kemp. The reality is things have withered since Jack got out of politics, and Republicans need to reengage. If this debate forces them to do that, it’s a good thing.”

In the states, several GOP governors have already struck a softer, more proactive tone. Ohio Gov. John Kasich, in particular, has expanded Medicaid coverage and has urged fellow Republicans to not use votes on poverty issues as a conservative litmus test.

Kasich often retells, as he did this past summer to reporters, what he once said to an Ohio lawmaker: “When you die and get to the meeting with Saint Peter, he’s probably not going to ask you much about what you did about keeping government small. But he is going to ask you what you did for the poor. You better have a good answer.”

But there is deep disagreement among Republican leaders and strategists over whether to embrace an economic-mobility agenda in the 2014 midterm campaigns. Some Republicans are wary of doing so, seeing it as playing on Democrats’ home turf, and think they are better off drawing voters’ attention to the rocky rollout of the health-care law and other problems plaguing Obama.

“People on the right say, ‘We don’t have to have much of a forward-looking agenda, and it gives a target to Democrats if we put things forward, and let the liberals crumble under their own weight,’” said Peter Wehner, a former adviser in the Reagan administration and both Bush administrations and a senior fellow at the Ethics and Public Policy Center.

But Wehner added that what may help Republicans in the 2014 midterms may hurt them in the 2016 presidential election, which will attract a larger electorate with more minorities. “The problem with the Republican Party is they’re out of step and out of tune and out of touch with many Americans,” he said.

That is the same message Democrats are trying to push to voters. Rep. Steve Israel (N.Y.), chairman of the Democratic Congressional Campaign Committee, said the 2014 elections will be about “who’s got your back.”

“Standing up for the middle class is part of the Democratic DNA,” Israel said. “We’ve always been the party of the middle class. We’ve always been the party of working families.”

State of the Union

Obama is expected to outline several populist policies in his State of the Union address this month, including an increase in the $7.25-per-hour federal minimum wage and more government spending on roads, ports and bridges, aimed at creating jobs.

White House advisers think these could be winning issues for Democrats in November’s midterm elections. But Gene Sperling, director of the National Economic Council, told reporters at the White House on Monday that the policy push is not motivated by campaign politics.

“If anybody suggests that somehow we want to fight for the minimum wage or extending emergency unemployment for political reasons as opposed to it being the right thing to do, well, I have a really good solution,” Sperling said. “Let’s get them done right now in a bipartisan way. Then everybody can share credit in doing something that’s the right thing for the American people.”

The prospects of such an agreement appear slim. House Speaker John A. Boehner (R-Ohio) has signaled a willingness to consider an extension of unemployment insurance, but he and other Republican leaders are looking for the benefits to be offset by spending cuts.

“I doubt we’re going to have a vote,” said Rep. Devin Nunes (R-Calif.), a Boehner ally. “You never say never, but a lot of Republicans think the big, bipartisan deal was the budget agreement, and we don’t see anything else on the table.”

The Republican Party is still haunted by the 2012 presidential campaign, when GOP candidate Mitt Romney’s remarks about the “47 percent” left an impression that the party is worried about the wealthy rather than the working class. Lanhee Chen, who served as Romney’s policy director, said he was encouraged by Rubio’s and Ryan’s efforts.

“Republicans tend to be behind the eight ball when it comes to these unemployment benefits and minimum-wage discussions,” Chen said. “So having a proactive agenda that helps people break into the middle class is an important enterprise for Republicans to be engaged in.”

Paul Kane contributed to this report.