WASHINGTON (AP) — The Biden administration has taken tremendous pride in methodically unveiling its agenda, particularly the $1.9 trillion pandemic relief measure the president hopes to trumpet over the next several weeks. But a growing list of unforeseen challenges is beginning to scramble the White House's plans.

In less than a week, two mass shootings have overshadowed President Joe Biden's “Help is Here” tour at which he planned to herald the ways his administration is helping Americans recovering from the pandemic. The White House has also struggled to respond to the growth in unaccompanied minors crossing the U.S.-Mexico border or blunt a nationwide effort by Republican legislatures to tighten election laws.

Biden's meticulous approach to the presidency is intended to serve as a stark departure from the chaos of his predecessor, Donald Trump. But the rapid developments over the past week are a reminder that even the most disciplined administration can only control so much.

“Every president and their staff make plans but every day the plans get blown up by reality," said Ari Fleischer, who was press secretary to George W. Bush when that administration's priorities were suddenly swamped by the Sept. 11, 2001, terrorist attacks. "Outside events intervene and force you to play defense or improvise or change your plans nearly every day. If you can’t juggle, you don’t belong in the White House.”

The juggle is intensifying at a particularly critical moment for Biden. The most valuable asset of presidents is their time, especially in their opening months in office, when the concerns of future elections are most distant. There were signs on Tuesday that the patience of Biden's diverse coalition may be fraying.

Two Democratic senators, Tammy Duckworth of Illinois and Mazie Hirono of Hawaii, condemned the lack of diversity in Biden's Cabinet. Scrutiny of those advising Biden has intensified after last week's shooting in Atlanta, which killed eight people, including six women of Asian descent. The violence came during a wave of attacks against Asian Americans over the past year.

Duckworth said she raised her concerns with the White House on Tuesday and she and Hirono threatened to withhold their votes on nominations until the administration addressed the matter. In a Senate that's evenly divided, such a move could have significant ramifications.

However, the two senators set aside their block on the nominees late Tuesday after securing the Biden administration's assurances more would be done. Press secretary Jen Psaki said the White House will add a senior-level Asian American Pacific Islander liaison "who will ensure the community’s voice is further represented and heard.”

Biden could soon face another fight if he follows through with his commitment to tighten gun regulations. After Monday's shooting at a Boulder, Colorado, supermarket that killed 10 people, Biden urged Congress to close loopholes in the background check system and ban assault weapon and high-capacity magazines.

Biden homed in on closing what is known as the Charleston loophole — provision in federal law that gives a gun seller discretion on whether to proceed with a sale if the FBI fails to determine within three business days whether a buyer is eligible to purchase a gun.

“That’s one of the best tools we have right now to prevent gun violence,” Biden said.

Biden, as a candidate, promised rapid action on gun control, including some steps on his first day in office. But the polarizing issue was quietly sidelined by the focus on the virus effort and the imperative to prioritize his agenda with narrow Democratic majorities in Congress and the legislative filibuster in place.

During the general election, Biden managed to quell much of the intraparty divisions that have so often riven Democrats by rallying them around a central purpose: defeating Trump.

After his election, his team adopted the same principle to unite the Democratic factions by again organizing around a common motivation: passing the massive $1.9 trillion COVID relief bill. There was to be no debate about priorities, Biden’s aides made clear to Democrats. The pandemic relief, which emphasizes vaccines and unemployment benefits, had to come first at a time of historic crises.

Publicly, Democratic lawmakers and groups signed on even as the behind-the-scenes jockeying began over what would come next. Biden aides have acknowledged that fighting over the sequence could become fierce, with disparate groups pushing for gun control, immigration, voting rights and climate change to become the centerpiece of the next White House push.

After the shootings, and a growing challenge at the southern border, West Wing aides in the last few days have held a series of meetings and virtual calls to strategize on how to proceed on the hot button issues, according to two White House aides not authorized to discuss private discussions. Biden urged advisers to move on gun control, the aides said.

West Wing aides privately acknowledge they were caught off guard by the increase in migrants at the border and the furor over the conditions of their detention. After only muted opposition to a pandemic relief bill none of them voted for, Republican lawmakers have seized on the border situation.

That’s making Democrats nervous. Some Democratic lawmakers have called for more transparency at the border while fearing such disclosure would allow Republicans to block the White House’s momentum.

Just before news of the Colorado shooting, White House aides leaked preliminary word about their next priority, a potentially $3 billion package with money for developing roads, hospitals, schools and green energy systems. But for that program, like other legislative priorities, the White House faces tough prospects for any Republican support and would be forced to proceed along a party-line vote.

That would require keeping all Democrats in line and deploying procedural maneuvers to pass legislation without Republican votes.

Biden, a Senate institutionalist, has long opposed modifying the filibuster, though aides have said he would give priority to his agenda over preserving the legislative tool if it comes to that.

But the move would face fierce opposition from Republicans in the minority and could also encounter headwinds among moderate Democrats like Sen. Joe Manchin of West Virginia, suggesting more political fights ahead.

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Associated Press writer Lisa Mascaro contributed to this report.