Former Vice President Mike Pence is entering the presidential fray, officially filing paperwork to launch his campaign for the White House among a field of candidates that includes his onetime boss, former President Donald Trump.

Pence on Monday filed the required form with the Federal Election Commission to mount a bid for the Republican presidential nomination, capping months of speeches, visits to Iowa and interviews that fueled speculation of a 2024 run. 

The former vice president is expected to launch his campaign with a speech in Iowa on Wednesday.

The Hawkeye State is a top priority for the emerging Pence campaign, and the former vice president is planning to visit the state almost weekly until the Iowa caucuses, CBS News reported last week. He is expected to make a considerable effort to appeal to evangelical voters, a crucial voting bloc in the state and one which he can appeal to given his own identity as an evangelical Christian.

In an interview earlier this year with CBS News, Pence twice declined to commit to supporting Trump if Trump is the Republican presidential nominee. Instead, Pence said he thinks "different times call for different leadership."

The former vice president has continued to incur Trump's wrath for refusing to reject the 2020 presidential election results before and after Trump's supporters swarmed the Capitol on Jan. 6, 2021. Pence appeared in April for more than seven hours before the grand jury investigating Trump's efforts to change the outcome of the 2020 election.

Pence joins a growing field of other well-known Republican candidates that includes Florida Gov. Ron DeSantis, Sen. Tim Scott and former Gov. Nikki Haley. With his campaign, Pence is expected to try to portray the contrast he presents with Trump and DeSantis. For Trump, Pence will likely highlight Trump's record on federal spending, and programs like Medicare and Social Security. With DeSantis, Pence is expected to bring up the Florida governor's antipathy with Disney, and his foreign policy stance on Ukraine.

In March, Pence denounced Trump in the strongest terms yet, saying the former president's "reckless words endangered my family and everyone at the Capitol that day." 

"History will hold Donald Trump accountable," Pence told an audience of politicians and journalists at the Gridiron Club Dinner in Washington, D.C.

Over the course of a vice presidency that was in many ways overshadowed by the Jan. 6 assault, Pence headed the White House Coronavirus Task Force to battle the COVID-19 pandemic, chaired the National Space Council and generally defended the administration's agenda, all while navigating Trump's capricious style. 

Before Trump chose him as a running mate in 2016, Pence was Indiana's governor and a congressman. As governor, Pence earned a reputation for his support of stringent abortion prohibitions and for signing a bill allowing businesses to reject gay customers on religious grounds. Pence, facing backlash, supported an effort to clarify the intent of that law.

Pence allies have been laying the groundwork for him for months. A super PAC has formed to support Pence, called "Committed to America," staffed by former aides to Georgia Gov. Brian Kemp and former Maryland Gov. Larry Hogan. 

Fin Gomez, Olivia Rinaldi and Robert Costa contributed reporting.

Kathryn Watson is a politics reporter for CBS News Digital based in Washington, D.C.