Hello and welcome to the US politics live blog.

A Senate committee later today is expected to give a quick confirmation to Markwayne Mullin, a first-term Republican senator from Oklahoma, to lead the Department of Homeland Security (DHS).

Mullin was nominated by US president Donald Trump after Kristi Noem was ousted amid public blowback against the administration’s aggressive approach to its mass deportation agenda, which resulted in the killings of two US citizens by immigration agents in Minneapolis.

The Democrats have forced the DHS into a partial shutdown until their demands for guardrails on immigration enforcement are met.

The issues at the heart of the standoff are set to come up this morning, when Mullin’s confirmation hearing begins before the Senate committee on homeland security and governmental affairs.

“I am grateful to President Trump for nominating me to lead the US Department of Homeland Security,” Mullin, who was elected to the Senate in 2022 after serving five terms in the House of Representatives, said on social media earlier this month.

“I look forward to earning the support of my colleagues in the Senate and carrying out president Trump’s mission alongside the department’s many capable agencies and the thousands of patriots who keep us safe every day.”

Republicans have praised his nomination, and their control of the Senate gives them the numbers to push his appointment through even if Democrats oppose him. Democrats have been quiet about Mullin, with party leaders saying that their demands for reforms to immigration operations won’t change regardless of who leads DHS.

The confirmation is expected to begin at around 9.30am ET.

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In other developments:

• A top counter-terrorism official in the Trump administration resigned over the ongoing war on Iran. Joe Kent, who reported to Director of National Intelligence Tulsi Gabbard, said in his resignation letter that he “cannot in good conscience” support the conflict.

• Gabbard responded in a statement that did not refer to Kent directly, but argued that Trump “is responsible for determining what is and is not an imminent threat”.

• The House oversight committee subpoenaed attorney general Pam Bondi to appear for a deposition on the Department of Justice’s handling of the Jeffrey Epstein investigation.

• The Senate passed a measure to start debate on the legislation to restrict voting in US elections in a number of ways, by a vote of 51-48, along mainly partisan lines, with only Lisa Murkowski, the Alaska Republican, crossing party lines.

• During the annual St Patrick’s Day Shamrock ceremony at the White House, Ireland’s prime minister, Micheál Martin, gently made the case for free trade and a rules-based order before presenting Trump with a bowl of shamrocks.

• While Trump and his aides spent much of Tuesday deriding Kent, critics of the administration pointed out that Kent’s ties to rightwing extremists meant that he was never fit for the role in the first place.