There was a sea of white as Democrats started to fill the chamber, ABC News' Capitol Hill team reports. The House Democratic Women's Caucus is wearing all white -- along with "Fighting for Reproductive Freedom" pins.

Other members are wearing blue to show support for the Israeli hostages taken after Hamas' October terror attack.

Some Republicans are wearing pins that say "Say her name: Laken Riley" in honor of the 22-year-old nursing student who was killed while out running on the University of Georgia's campus last month. The suspect charged in her death is a Venezuelan migrant who is illegally in the U.S., officials have said.

Some Republican lawmakers are also wearing buttons that read: "Stop the Biden border crisis."

As ABC News is reporting, Biden's foreign policy has come under fire from left, but the right also has something to be unhappy about. Whether to continue to aid Ukraine in its fight against Russia’s two-year-old invasion has opened up as a major difference between the two parties. House Speaker Mike Johnson has stopped a Senate aid package from passing in his chamber, and continuing to fund the war is becoming more unpopular with Republican voters.

On the left, Democrats have disapproved of Biden’s response to the Israel-Hamas war. To put pressure on the administration, protesters launched a campaign to vote "uncommitted" in various Democratic primaries around the country, and Vice President Kamala Harris has recently joined calls for a cease-fire as the humanitarian crisis in Gaza becomes increasingly dire. Biden may want to work to address concerns within his own party.

-Monica Potts, 538

Protesters are staging a sit-in on Pennsylvania Avenue near the Capitol ahead of Biden's speech -- demonstrating in support of the Palestinian civilians in Gaza suffering amid the Israel-Hamas war.

Biden has faced heavy criticism from the progressive wing of the Democratic Party and many in the Arab American community over his response to the conflict, in which he has sought to balance his sympathy for civilians with support for Israel's campaign after Hamas' October terror attack.

Nonetheless, many critics have called on him to more forcefully push for an immediate stop to all fighting as conditions remain dire for civilians in the Gaza Strip. Cease-fire advocates have interrupted other Biden events in the past few months, including an abortion rights campaign rally in January.

Biden in his speech on Thursday night is expected to announce an "emergency" military mission to construct a pier in the Mediterranean Sea on Gaza's coast to get humanitarian aid into the area, according to senior officials.

Meanwhile, family members of Americans who thought to still be held by Hamas will be in the audience as guests of Republican lawmakers.

Kate Cox, a Texas woman who had to go to New Mexico for an abortion after she and her doctor said her pregnancy could have threatened her life, explained how difficult her experience was to ABC News before attending the State of the Union as a guest of the president and first lady Jill Biden.

Cox said her fetus was diagnosed with trisomy 18, a condition described as incompatible with life, but had to go to New Mexico for an abortion after a court ruled that the procedure would violate Texas' ban.

"It was really heartbreaking because we were so excited for our third baby. It's the hardest news I've ever received," she told ABC News' Rachel Scott.

"And it's hard to walk around pregnant with a belly, especially usually with my other two kids, when people ask you, you know ... 'What are you having? Do you have a name? Are you going to have a baby shower?' It's really hard when, you know, how do you explain that there's not going to be a baby, that she'll never survive?"