WASHINGTON – Shutdown pressure on President Trump mounted Wednesday as House Speaker Nancy Pelosi called on him to delay his Jan. 29 State of the Union address and his own economists acknowledged the prolonged standoff was having a greater economic drag than previously thought.

In a letter to Trump, Pelosi cited security concerns, noting that both the Secret Service and the Homeland Security Department are entangled in the partial government shutdown, now in its fourth week. She added that unless the government reopens this week, they should find another date or Trump should deliver the address in writing.

The White House did not immediately respond to the high-stakes move on the 26th day of the shutdown, as Trump and Democrats are at an impasse over Trump’s demands for $5.7 billion to build a wall along the Mexican border.

Pelosi is refusing money for the wall she views as ineffective and immoral; Democrats say they will discuss border security once the government has reopened.

The White House said Trump signed a bill Wednesday that will require some 800,000 federal employees to be compensated for wages lost or work performed during the partial government shutdown.

The signing of this bill I authored with @SenatorCardin is a good first step in providing relief for federal workers. While guaranteeing back pay will help give some peace of mind, a compromise must be reached to bring this shutdown to an end. https://t.co/RefRPmJksr

— Sen. Susan Collins (@SenatorCollins) January 16, 2019

Wednesday’s bill signing was closed to the media. The House and Senate had voted to give the workers back pay whenever the federal government reopens.

Trump met a bipartisan group of lawmakers Wednesday that included seven Democrats. Two people who attended the White House meeting agreed it was “productive,” but could not say to what extent Trump was listening or moved by the conversation.

The people, who spoke on condition of anonymity to discuss the event candidly, said it seemed at some points as if people were talking past each other. Lawmakers talked about the shutdown’s effect on their constituents and advocated for “border security.” Trump and others on-and-off used the term “wall.” It was not clear if progress had been made, by those accounts.

Meanwhile a group of Republican senators headed to the White House later Wednesday.

Many Republicans are unwilling to sign on to a letter led by Sen. Lindsey Graham, R-S.C., and Sen. Chris Coons, D-Del., to reopen the government for three weeks while talks continue.

“Does that help the president or does that hurt the president?” asked Sen. Mike Rounds, R-S.D., among those going to the White House. He has not signed the letter. “If the president saw it as a way to be conciliatory, if he thought it would help, then perhaps it’s a good idea,” he said. “If it’s just seen as a weakening of his position, then he probably wouldn’t do it.”

While Sen. Susan Collins, R-Maine, said she has signed, others said Republican support was lacking. “They’re a little short on the R side,” said Sen. Joe Manchin, D-W.Va., another leader of the effort.

Other lawmakers are floating additional plans, but Graham was skeptical any would breakthrough.

“I am running out of ideas,” he said.

“The Democrats are not going to negotiate with the government shut down,” he said. “People in the White House don’t like hearing that. I don’t know what to tell them other than what I actually think.”

Even as administration officials projected confidence in their course, Trump’s economists indicated the shutdown is causing greater economic harm than expected.

Kevin Hassett, chairman of the White House Council of Economic Advisers, said Tuesday the shutdown is slowing growth more than predicted.

An economic shift could rattle Trump, who has tied his political fortunes to the stock market and repeatedly stressed economic gains as evidence that his tax-cut package and deregulation efforts are succeeding. Economic optimism had already cooled somewhat as Trump’s trade fight with China shook the markets.

Hassett told reporters the White House is doubling its estimate of the strain on the economy of the shutdown, and now calculates that it is slowing growth by about 0.1 percentage points a week.

With the shutdown in its fourth week, that suggests the economy has lost nearly a half-percentage point of growth so far, though some of that occurred at the end of last year and some in the first quarter of this year. Hassett said the economy should get a boost when the government re-opens.

Previous White House estimates of the impact did not fully take into account the effect on people who work for private companies that contract with the government to provide services, Hassett said.

While the hit to the overall economy so far remains slight, economists foresee real damage if the shutdown drags into February or beyond.

Roughly 1 million government employees and contractors aren’t being paid. Travel plans are compromised by shuttered federal parks and airport delays. Some Americans trying to start small businesses face delays in obtaining the required tax identification number from the IRS.

White House spokeswoman Sarah Huckabee Sanders told reporters that the economy remained strong.

“I know there has been some impact, but at the same time we’re focused on the long term economic principles the president has laid out,” she said.

The House and Senate said they will cancel a recess later this week if the shutdown continues, which seemed likely.

The president, on a conference call with supporters Tuesday, showed no signs of backing down.

“We’re going to stay out for a long time, if we have to,” Trump said. He also suggested the partial shutdown, which has clogged airport security lines and shuttered federal agencies, was going smoothly.

Behind the scenes, though, the administration and its allies on Capitol Hill are warily eyeing the next payday. They hope to reach a resolution before a Tuesday deadline, when they’ll need to prepare the next round of paychecks for workers who have been seeing zeros on their pay slips.

Trump, who a week ago seemed intent on declaring a national emergency in order to build the wall, has turned his attention back to Congress as polling suggests he is taking much of the blame for the standoff.

Associated Press writers Chris Rugaber, Darlene Superville, Matthew Daly, Jonathan Lemire, Alan Fram, Andrew Taylor, Laurie Kellman, Elana Schor and Ken Sweet contributed to this report.