WASHINGTON — (CNN) President Donald Trump on Wednesday will start to reshape US immigration enforcement policies via executive order, taking his first steps toward fulfilling some of the most contentious pledges that defined his campaign.

Trump will hurl federal officials into the task of building a wall on the US-Mexico border, call for boosting border patrol forces and look to increase deportations of undocumented immigrants by signing two executive orders during a visit to the Department of Homeland Security, the agency that would implement those actions, a source familiar with the plan told CNN.

The executive orders will also seek to end sanctuary cities and the practice of releasing undocumented immigrants detained by federal officials before trial.

Construction of the wall could begin in months, but planning for the massive project is “starting immediately,” Trump said Wednesday in an interview with ABC News.

Trump confirmed his plans to build the wall with federal funds and then seek reimbursement from Mexico, an idea Mexico has resisted. But negotiations, he said, would begin “relatively soon.”

“I’m telling you there will be a payment. It will be in a form, perhaps a complicated form,” Trump said.

The actions will send alarm bells ringing in immigration activist circles, where questions still are swirling about whether Trump would truly implement many of the hardline immigration policies he articulated during his campaign. Trump’s planned actions leave little doubt about whether his immigration policies as president would differ from his campaign rhetoric.

There remained little question, for example, about whether Trump would push to increase deportations of undocumented immigrants. One of Trump’s executive orders will call for tripling “enforcement and removal operations/agents” of the Immigration and Customs Enforcement agency, which is charged with arresting and deporting undocumented immigrants living in the US. And his executive order also called for a 5,000-person increase in Customs and Border Protection personnel.

Trump’s executive actions are not expected to address those of his predecessor President Barack Obama that signed safeguarding undocumented immigrants who came to the US as children or who are parents of lawful US residents from deportation, which Trump during his campaign signaled he would repeal.

White House press secretary Sean Spicer has said Trump wants to prioritize the removal of undocumented immigrants who have committed crimes in the US, but has refused to say whether deportation priorities would change. Trump during his campaign called for the deportation of all undocumented immigrants living in the US, though he signaled the “good ones” could return to the US under an expedited process.

Trump’s hardline immigration rhetoric and policy proposals during the campaign often put him at odds not only with Democrats but with many in his own party who called his proposal to build a wall on the US-Mexico border unnecessary and his calls for mass deportation cruel.

Trump persevered in his hardline rhetoric throughout the campaign, resisting efforts to pivot to a more moderate stance on the issue in the general election despite calls to soften his rhetoric.

Now, his actions will take a big first step toward satisfying his political base of support that hitched to his campaign amid Trump’s bold promises of building a wall, deporting undocumented immigrants and in the process creating a safer country, despite a total lack of evidence tying undocumented immigrants to higher crime rates.

Trump catapulted his campaign into controversy and relevance with his announcement speech in June 2015, in which he pledged some of the hardline immigration policies he was set to enact and decried undocumented immigrants as criminals and “rapists.” Trump never apologized for those comments.