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(CNN) —  

Illegal immigration, the border wall, Democrats, “fake news” and even “Cheatin’ Obama.”

These are the base-rallying call signs President Donald Trump has deployed on Twitter in the last week, just as he is facing a rare onslaught of criticism from pockets of his right-wing base over a $1.3 trillion spending measure he signed that didn’t include new border wall funding. The law included about $1.6 billion for border security.

The lengthiest of his recent Twitter rants came in the last three mornings, after he spent the weekend at Mar-a-Lago venting with allies and fielding the concerns of conservatives who worry he hasn’t done enough to mollify his political base’s demands for action on illegal immigration.

Privately, sources close to the President and the White House say Trump is also increasingly turning to the 2018 midterm elections and has focused on how he can help deliver high turnout numbers among his supporters. Motivation his base is something the President and some of his allies believe will be key to keeping Congress in Republican hands and thus help avoid potential impeachment proceedings from a Democratic House.

Five sources close to the White House offered varying interpretations of whether there is a strategy behind the uptick in Trump’s tweets. But all agreed the activity has served to energize – or reassure – his political base and provides a preview of how Trump plans to approach the upcoming elections.

“He’s only going to rev this up. He’s looking at targets that the base hates,” one source close to the White House said. “The enthusiasm gap between ‘the resistance’ and ‘the base’ is now palpable.”

Trump’s weekend at Mar-a-Lago only served to solidify his ruefulness at the massive spending measure he signed a week earlier. There, Fox News personalities such as Sean Hannity and Jeanine Pirro amplified the criticism of the bill found in some conservative circles where frustration at the lack of funding for a border wall reached a fever pitch.

The loudest of those criticisms reached the President through TV screens, where the conservative firebrand Ann Coulter excoriated the President for failing to get border wall funding. One source said Trump was “rattled” by Coulter’s criticism, while another said he was “aggravated.”

Responding to criticism

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Does Trump have a strategy with Mexican border and Syria?

In its wake, Trump has issued a series of social media invectives to signal his commitment to stemming illegal immigration and building the wall that became as prominent a staple of his campaign as the red “Make America Great Again” hats donned by his supporters.

“Border Patrol Agents are not allowed to properly do their jobs at the Border because of ridiculous liberal (Democrat) laws like Catch & Release,” Trump tweeted on Sunday.

On Monday, he lamented the lack of “effective border laws” in the US, warned “our country is being stolen!” and accused Democrats of wanting “No Borders, hence drugs and crime!”

On Tuesday – between tweets about “fake news” – he offered still more on the topic: “The big Caravan of People from Honduras, now coming across Mexico and heading to our ‘Weak Laws’ Border, had better be stopped before it gets here.”

But if Trump’s aim is to mollify the criticism he is facing from the right, one top Trump ally in Congress predicted that won’t be enough.

“Most Republican members are just getting beat up because of the omnibus vote,” said the GOP lawmaker, who spoke on condition of anonymity to speak more candidly. “The danger is there was a day in time when a few tweets would reassure conservatives in Trump districts. The vote on the omnibus doesn’t allow for a tweet to reassure them anymore.”

Reached by email, Coulter offered a similar analysis: “As I have said, they don’t call it ‘The Great Tweet of China.’ “

Hit a wall on the wall?

01:32 - Source: CNN
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In the 11 days since he signed the spending bill that left Coulter and conservatives in Congress upset, Trump has continued to grumble about the lack of funding for the wall and privately blamed both members of his administration and Republican leaders in Congress for negotiating an unsatisfactory bill, three sources close to the President said.

“He understands that the building of the wall was a central component of the campaign and it’s very difficult going into the ‘18 cycle not having built it,” one source close to Trump said.

But a separate source familiar with the conversations said Trump has coupled his frustration with the lack of funding with private insistence that the wall is being built – pointing to the replacement of existing fencing on the southern border – and that it must simply be marketed better to the public.

Trump appeared to make an attempt at that last week when he tweeted photos of new fencing being installed on the border and wrote: “Great briefing this afternoon on the start of our Southern Border WALL!”

That messaging – from a President who is now without a communications director other than himself – is likely to increase as the midterms near. If not disappointed in the level of action on border security, Trump has worried that some of his supporters may be complacent.

“History says that when you win the presidency, that party doesn’t do so well in the midterms because people get complacent. They get complacent,” Trump told a crowd in Ohio last week. “We cannot be complacent.”

The President’s advisers inside and outside the White House have convinced him he can be the motivating factor, pointing him to figures that suggest he helped narrow the Republican deficit in a Pennsylvania congressional race by hitting the campaign trail days before the election last month. The Republican candidate still lost the race narrowly, despite the fact that Trump won the district by 20 points.

Base-pleasing tweets like he has issued in the last week are likely to play into that effort, sources close to Trump said, noting that the tweets are a tried-and-true playbook of his 2016 campaign.

But some allies still hope Trump will also use his Twitter account not just to pump up his base, but also to tout a growing economy and the tax cut bill that Republicans plan to run on as their 2018 platform.

“He’s proven that he can drive the news cycle, but drive it for good,” said Barry Bennett, a former Trump campaign adviser. “Because if we talk about the economy and where it’s going, we’re not going to lose the House.”

Of course, tweets aimed at the base will help too, Bennett said.

“What you gotta do is remind them why we’re fighting together,” he said. “It always works.”

CNN’s Kevin Liptak contributed to this report.