When Republican Rep. Jeb Hensarling sat down with colleagues and constituents at a recent Chamber of Commerce lunch in Dallas, the first question he faced was whether Congress planned to address immigration policy and a burgeoning border crisis.

"I'm supposed to do this in 30 seconds?" he joked, noting the issue's complexity. While he was optimistic about long-term prospects for dealing with border security and immigration, he said, "between now and the end of this Congress, I'm a little less sanguine about it."

It has been a question heard repeatedly by lawmakers this month in "town hall" district meetings punctuated -- and sometimes dominated -- by concerns and angry outbursts over immigration policy and the crisis caused by a flood of child migrants at the southwestern border in recent months.

Those summer town halls have provided lawmakers a first-hand glimpse of growing discontent among Americans over U.S. immigration policy. Seventy percent of Americans -- including 86 percent of Republicans -- believe undocumented immigrants threaten traditional U.S. beliefs and customs, according to a Reuters/Ipsos poll conducted in mid-July.

Those fears have been exacerbated by the recent wave of illegal child migrants from Central America. An issue that had been simmering is now hotting up as voters prepare to go to the polls in congressional elections due in November.

The anger and frustration expressed in the town halls suggests there will be a fierce debate when U.S. lawmakers return to Washington on Sept. 8 and take up proposals to address a flood of child migrants crossing the southwestern U.S. border.

While conservative anger has not approached the levels seen during the healthcare debate in August 2009, when town halls across the country were frequently disrupted, members of both parties have been confronted on the issue.

From border states like Texas to less likely hot spots like Oregon, Colorado, and New York, Democratic and Republican lawmakers have heard a steady stream of questions and complaints from voters -- most pushing for a crackdown on illegal immigration and some worried about what they see as Washington's inaction.

'Anger is palpable'

"I hear it everywhere I go," said Oregon Republican Greg Walden, who travels the country in his role as chairman of the National Republican Congressional Committee.

"The anger is palpable," Hensarling, a six-term conservative congressman who is often identified by colleagues as a possible next Speaker of the House, told Reuters.

Local media reported police were called to a meeting in Hollister, California hosted by Democratic Rep. Sam Farr after an audience member shouted at Farr and the crowd about the dangers posed by the child migrants.

A town hall hosted by Democrat Jared Polis of Colorado featured constituents shouting at Polis and each other, and applauding those who contradicted him, on a range of issues, most prominently immigration, a local newspaper said

"We've had seven town halls, and immigration is the No. 1 issue that comes up," Polis told Reuters.

A series of executive actions on immigration that President Barack Obama plans to unveil next month could further intensify the debate. The policy changes are likely to fuel Republican accusations that Obama is overstepping his authority.

'There's a lot of fear'

Conservative concerns over immigration have been merging with Republican worries about Obama's healthcare, economic and foreign policies, Oregon lawmaker Walden said.

"It's morphed into something bigger than a debate over fixing our broken immigration system -- it's a piece of the overall sense that things are on the wrong track in this country," he said.

Hensarling said "there's a lot of fear about that, about a president who has a pen and a phone, but doesn't seem to have a copy of the Constitution."

But Polis said even left-leaning voters are growing frustrated by the lack of progress in Congress on a long-term policy fix. A bipartisan June 2013 immigration reform bill that passed the Senate has been stalled in the House.

Opinion polls show concerns about immigration extend to every region of the country, although they are most acutely felt in the southwestern states near the Mexican border.

Despite voter concerns, political strategists from both parties say immigration is unlikely to be the deciding factor in any battleground midterm congressional race. Republicans must pick up six seats to reclaim control of the Senate in November, and are heavily favored to pad their comfortable majority in the House of Representatives.

Only three Republican Senate contenders -- New Hampshire's Scott Brown, Michigan's Terri Lynn Land, and Arkansas' Tom Cotton -- have run advertisements about immigration. Vulnerable incumbents have largely avoided potentially controversial town halls that could force them to answer tough questions on the topic.

National Democrats believe roughly two dozen House districts could see immigration play a role in November’s result, and pundits frequently point to Colorado’s competitive Senate race as the likeliest immigration battleground.

But the candidates in that contest have sparred over other issues, and Republican Cory Gardner earlier this month voted with a mostly Democratic bloc not to repeal Obama’s 2012 measure providing a stay of deportations to young undocumented migrants.

[Image via Agence France-Presse]