Border crisis roils key campaigns in the battle for Congress The controversy at the U.S.-Mexico border is factoring into key midterm races.

Candidates across the country and from both parties in key midterm races are grappling with how to respond to the backlash over the controversial separation of undocumented immigrants and their young children at the U.S.-Mexico border.

It is a situation that is becoming more complicated by the day and by a president who as recently as Monday doubled down on his charged rhetoric.

Texas Rep. Will Hurd, who faces a competitive race this fall in a swing district that spans some 800 miles along the U.S.-Mexico border, pushed back on the policy Monday morning, the day after Department of Homeland Security Secretary Kirstjen Nielsen's denial over the weekend that the Trump administration has a policy of separating families at the border.

There is currently no law mandating separation of families, and the so-called "zero-tolerance" policy on illegal border crossings, set forth by Trump and implemented by Attorney General Jeff Sessions, has come under sharp criticism by lawmakers, advocates, and the religious community. The enforcement of that policy has led to children being separated from parents caught illegally crossing the border.

"This is part of the problem with this administration on this policy. There's different elements of the government that don't understand what's really going on," Hurd told NPR's Morning Edition in an interview, "This is just absolutely unacceptable, taking kids from their mothers is not preventing terrorists or drugs from coming into this country."

Nielsen defended the administration and her department's handling of the situation Monday at a conference of the National Sheriff's Association in New Orleans.

"It's important to understand that these minors are very well taken care of. Don't believe the press," Nielsen said.

Hurd's Democratic opponent Gina Ortiz Jones, a U.S. Air Force Veteran a first-generation American, joined a march to Tornillo, Texas, a port of entry into the United States, to protest the policy alongside other Democratic candidates running in Texas this cycle, including U.S. Senate candidate and El Paso Congressman Beto O'Rourke and gubernatorial candidate Lupe Valdez.

O'Rourke, the Democratic challenger to incumbent GOP Sen. Ted Cruz, directly disputed Nielsen's claim that the administration does not have a policy of separating families, tweeting Monday morning, "You do. I’ve met moms held in cells w their young kids before you take them. Seen the kids behind cyclone fences after you’ve “unaccompanied” them. Been w parents prosecuted like common criminals for doing what any parent would do, through tears asking me where their kids are."

Lizzie Pannill Fletcher, the Democratic trying to unseat GOP Rep. John Culberson in a swing district in the Houston suburbs, urged Congress to protect both families seeing asylum at the border, and the Deferred Action for Childhood Arrivals (DACA) program.

"There is no doubt that we need to fix our immigration system, and the residents in this district have told me how concerned they are about doing so," Fletcher said in a statement provided to ABC News, "Right now, Congress needs to perform its essential function to check the Administration’s devastating separation of asylum-seeking families at the border and needs to keep the promises we made to DREAMERs."

While the controversy has become front and center in many high-profile Texas races, it's impact has spread to races across the country.

Nevada

In Nevada, Democratic Rep. Jacky Rosen, who is hoping to unseat GOP Sen. Dean Heller, joined a group of her colleagues in condemning the separation of families at the border.

"The images we’re seeing of children crying alone while being held in detention centers are heart-wrenching and demand action from Congress," Rosen wrote in a press release last week, "Parents are being separated from their kids every day, even though there is no mandate in the law requiring border agents to do so."

In a break from the Trump administration, Heller said he does not support the policy of separating families, and called on Congress to act to solve the problem.

"Senator Heller doesn’t support separating children from their families, and he believes that this issue highlights just how broken our immigration system is and why Congress must act to fix it," read a statement from Heller's office provided to ABC News.

In a sign that Democrats appear united in their opposition to the policy, California Democratic Sen. Dianne Feinstein announced Monday that the party's entire caucus in the Senate supports her bill to end the separation of families at the U.S. Mexico border, dubbed the "Keep Families Together Act."

Florida

In Florida, competitive races for the U.S. Senate and governor's mansion, coupled with the political omnipresence of sitting Gov. Rick Scott, has generated a number of passionate responses from candidates of both parties.

"First the reports you see, it’s disturbing, it’s disgusting. It just shows you that Congress has not done their job," Gov. Scott, who is mounting a bid to unseat Democratic incumbent Sen. Bill Nelson, told a local television station, "We need to have an immigration policy that people understand, we need to secure our borders, but we can’t have people being treated unfairly."

Andrew Gillum, the current mayor of Tallahassee and a Democratic candidate running in the race to succeed Scott as the state's next governor, lambasted Scott for not speaking out forcefully enough during a "moral crisis."

"I demand that Governor Scott — who is now asking for our vote to be our next Senator — stand up to the Trump Administration and support S. 3036, the Keeping Families Together Act," Gillum wrote in a statement released Sunday, "Yesterday he didn’t have much to say on this crisis, but in times of moral crisis we need our leaders to step forward. We demand the reconciliation and reunification of families."

Former Democratic Rep. Gwen Graham, another contender in the gubernatorial race, weighed in with a short response to President Trump's Monday morning barrage of immigration-related tweets.

Arizona

In the border state of Arizona, which is also holding elections for the U.S. Senate and governor's mansion in November, one Democratic gubernatorial candidate, David Garcia, called out Republican Governor Doug Ducey for what he claimed was his "silence" on the controversy.

"Ducey is either afraid of Trump or he agrees with him; either way his silence is de facto support for Trump. Arizona needs a governor with the guts to say to Trump that what he is doing is inhumane, un-American and it must stop now," Garcia wrote in a statement last week.

Ducey, who officially launched his re-election campaign Monday, did not respond to ABC News' request for comment on the situation at the U.S.-Mexico border.

Kelli Ward, a former GOP state legislature now running for the U.S. Senate seat vacated by Republican Jeff Flake, attacked both a Republican opponent of hers and the likely Democratic nominee in the race, Rep. Kyrsten Sinema over the lack of progress on the immigration issue in Congress.

"Congress has repeatedly failed to address border security, one of the top issues for voters in Arizona, while my opponents Reps. Martha McSally and Kyrsten Sinema have allowed this humanitarian crisis to persist for years -- under several administrations -- without making any effort to fix it," Ward wrote in a statement provided to ABC News, "I remain committed to securing our border and building the wall, in the process ensuring we keep Americans safe and families together."

Ward's statement notably contained no mention of another one of her opponents in the Republican primary, former Maricopa County Sheriff Joe Arpaio.

Arpaio's campaign re-iterated that the former sheriff believes the United States is a nation of laws and that the immigration laws on the books should be enforced.

"Why aren't we holding the parents of these kids responsible? They know there is an inherent risk when they make this journey to cross the border illegally," Chris Hegstrom, Arpaio's communications director, quoted Mr. Arpaio as asking.

Arpaio was pardoned by President Trump last year after being found guilty on criminal contempt charges stemming from his refusal to stop imprisoning suspected illegal immigrants.

California

In California, a Democratic running in a heated congressional race in Orange County called the separation of families "immoral."

"Immigrant children should not be separated and put in cages. Refusing abused women seeking asylum is immoral," Democratic candidate Harley Rouda, who is one of two Democrats hoping to take on GOP Rep. Dana Rohrabacher, tweeted last week.

Gil Cisneros, a Democrat running in California's 39th Congressional District hammered the Trump administration for what he called a "heartless policy."

"The Trump administration’s policy does nothing to strengthen our border security, nor does it address any of the issues affecting our immigration system. There is no justifiable reason to rip apart these families, yet this administration refuses to accept responsibility for its decision," Cisneros wrote in a statement released Tuesday.

David Valadao, another Republican running in another swing district located in California's Central Valley, released a statement Monday saying the practice of separating young children from their families is "unacceptable."

"The substantial increase of minors at our southern border is both a humanitarian and national security crisis," Valadao wrote in his statement, "While we must work towards a solution that reduces the occurrence of illegal border crossings, it is unacceptable to separate young children from their parents. This is exactly why passage of a compromise solution, such as that being discussed in Congress right now, is absolutely necessary."

Across the country, from Washington to Wisconsin to Mississippi, candidates attempted to navigate the treacherous political waters created by the border crisis.

"As a father I feel great concern any time I see a child crying out of fear or desperation, anywhere in the world," Wisconsin Republican Senate candidate Kevin Nicholson wrote in a statement Tuesday, going on to attack the state's sitting Democratic incumbent, "In this case, I'm also angry with the many entrenched Washington politicians – like Tammy Baldwin – who have worked mightily to encourage the 'catch and release' illegal immigration policies that put innocent children in this position in the first place."

Mike Espy, a former congressman and U.S. Secretary of Agriculture who is now running for the U.S. Senate in Mississippi, called the policy "misguided" and said a solution can be found "with the right combination of common sense and compassion."

While candidates in swing states and districts spar over the controversy, President Trump again inserted himself into the debate.

Just this morning, the President continued to fume on Twitter over inaction on the issue of immigration, pointing the finger once again at Democrats who he claims aren't coming to the table to negotiate, a claim many Democrats dispute and say is disingenuous.

"If the Democrats would sit down instead of obstructing we could have something done very quickly," President Trump said Monday from the White House at a meeting with the National Space Council.

In a rare policy statement released over the weekend, first lady Melania Trump urged Congress to find a bipartisan solution to the issue.

"Mrs. Trump hates to see children separated from their families and hopes both sides of the aisle can finally come together to achieve successful immigration reform. She believes we need to be a country that follows all laws, but also a country that governs with heart," a statement released Sunday from the First Lady's Communications Director Stephanie Grisham read.

Former first lady Laura Bush called the separation of families at the border "cruel" in an op-ed published over the weekend in the Washington Post.

"I live in a border state. I appreciate the need to enforce and protect our international boundaries, but this zero-tolerance policy is cruel. It is immoral. And it breaks my heart," Bush wrote.

Amidst the back and forth between campaigns, the president, and multiple cabinet members is a Congress that continues to struggle to find a bipartisan consensus on the issue of immigration.

Neither of the immigration bills slated for a vote this week in Congress looks like they have garnered enough support from a majority of the Republican Party or a coalition that stretches across party lines.

The House is expected to take up two GOP immigration bills this week that will each include a provision Republicans say would keep unaccompanied alien children together with parents and legal guardians while in the custody of the Justice Department or Department of Homeland security. Critics argue that the provision would allow the government to keep families in custody indefinitely.

ABC News' Matthew Fuhrman, Meghan Keneally, Lissette Rodriguez, Rachel Scott and Benjamin Siegel contributed to this story.