WASHINGTON — President Trump said on Tuesday that the United States needed “a good ‘shutdown’” this fall to force a partisan confrontation over federal spending, and suggested that he might move to reverse longstanding Senate rules that effectively require a supermajority to approve most major pieces of legislation.
The declarations, in a pair of posts on Twitter, appeared aimed at defending a spending package that Congress is likely to clear this week, but that fails to accomplish many of Mr. Trump’s stated goals, including any money to build a wall on the southern border that was his most talked-about campaign promise. Conservative activists have decried the agreement as one that does not address their priorities, but the White House has signaled that the president will accept it rather than set off a government shutdown.
The Twitter messages were also an indication of the degree to which bipartisan negotiations in Congress on the spending bill and others, including a health care overhaul that appeared on Tuesday to be stalled yet again, have bedeviled Mr. Trump at this early stage of his presidency, forcing him to bow to political realities to which he had insisted he was immune.
“The reason for the plan negotiated between the Republicans and Democrats is that we need 60 votes in the Senate which are not there!” Mr. Trump said in one post, an apparent reference to the spending package.
The solution, he said, was either to elect more Republican senators in 2018, the next midterm elections, “or change the rules now to 51%.” That appeared to refer to scrapping the so-called filibuster that allows any senator to insist on a three-fifths vote, rather than a simple majority, to act on legislative matters.
Republicans already moved last month to eliminate the use of the tactic for Supreme Court confirmations, allowing them to move forward with the approval of Justice Neil M. Gorsuch over near-unanimous Democratic opposition.
“Our country needs a good ‘shutdown' in September to fix mess!” Mr. Trump said.
The White House moved swiftly on Tuesday to counteract Mr. Trump’s contention that he had been forced into an agreement he dislikes, claiming victory on the spending package and arguing that the White House had actually outfoxed Democrats who were spoiling for a shutdown.
“They wanted to try and make this president look like he could not govern,” Mick Mulvaney, Mr. Trump’s budget director, told reporters in a conference call. “They wanted to make this president look like he did not know what he was doing, and he beat them on that at the very, very highest level.”
He praised the large increase in military spending in the bill, which dwarfed the money for domestic programs, and said that although no wall funding had been included, increases for border technology, maintenance and repairs would help beef up security on the line between the United States and Mexico.
Democrats, Mr. Mulvaney added, “were desperate to show that we were not reasonable, and we completely destroyed that narrative by negotiating this deal. This is a huge victory for the president.”
But by publicly courting a future shutdown, an extraordinary move for a sitting president, Mr. Trump instead seemed to be confirming his reputation for rash statements that may yield little in the way of follow-through.
“President Trump may not like what he sees in this budget deal, but it’s dangerous and irresponsible to respond by calling for a shutdown,” said Senator Patty Murray, Democrat of Washington and the ranking members of the appropriations committee. “Hopefully, Republicans in Congress will do for the next budget what they did for this one: ignore President Trump’s demands, work with Democrats, and get it done.”
Indeed, Republicans appeared eager to ignore Mr. Trump’s latest outburst and focus on an agreement they said was worth supporting.
“How many times have I had this: ‘Do you agree with a tweet this morning?’ ” House Speaker Paul D. Ryan, Republican of Wisconsin, joked after being asked about the president’s Twitter statements.
Mr. Ryan said he did “share the president’s frustration” but noted that bipartisan support was required for spending measures.
“Having said all that, I feel very good about the wins we got with the administration in this bill,” Mr. Ryan said.
Many conservative activists were not so enthused. Heritage Action, a conservative group, urged lawmakers to vote “no” on the measure, saying it “woefully fails the test of fiscal responsibility and does not advance important conservative policies.”
Charles Krauthammer, the conservative commentator, said Monday on Fox News: “Trump got rolled. The Republicans got rolled.”
Anti-abortion rights groups also objected because the measure fails to defund Planned Parenthood, a goal that Mr. Trump has said he shares.
“One has to wonder if the Democrats are the majority party in Congress,” said Mat Staver, chairman of Liberty Counsel, a group that promotes socially conservative policies. “We urge President Trump to keep his promise and we call on the Republican Congress to start leading and stop supporting failed policies.”
Mr. Mulvaney said the move to defund Planned Parenthood would wait for enactment of the health care overhaul, a prospect that seemed to be growing more remote, not less, on Tuesday as key Republicans said they could not support it.
“Let there be no mistake about this administration’s commitment to the pro-life movement,” he told reporters during the conference call.
On Tuesday, Senator Mitch McConnell of Kentucky, the majority leader, praised the spending bill, which he said the Senate would vote on later this week, and did his best to portray it as a win for his party.
“This legislation will promote a number of American and conservative priorities,” he said, noting its attendant funding increases for border security and the military, and cuts to climate control programs championed by the Obama administration.
Democrats said Mr. Trump’s tactics assured that partisan rancor would continue to hang over Capitol Hill in the coming months.
“Threatening to shut down the government, on the heels of a successful, bipartisan agreement, is a sour and shameful note to kick off negotiations” for the coming year, said Senator Patrick Leahy, Democrat of Vermont. “I hope the president does not seriously wish to have the consequences of a government shutdown resting squarely on his shoulders.”
Correction: May 2, 2017
An earlier version of this article referred incorrectly to the filibuster. It allows any senator to insist on a three-fifths vote — not a two-thirds vote — rather than a simple majority to act on legislative matters.