[5] The politics of the Oregon Territory were largely dominated by the generally states' rights Democratic Party with a vocal pro-slavery component.

[6] A serious opposition first began to emerge in the aftermath of the bitter and costly Rogue River Wars of 1855 to 1856, centered around the growing anti-slavery sentiment nationally and the increasing threat that the Democratic Party would hasten the expansion of slavery in Oregon.

[6][7] A first convention of Republicans in Oregon was held in May 1856 at the Lindley schoolhouse in Jackson County, with the gathering called for the nomination of candidates to appear on the June 1856 territorial ballot.

[9] Republican county conventions were held in Clackamas, Washington, Marion, Linn, and possibly one or two other locales around the state.

[11] The year 1857 was marked by preparations for future Oregon statehood, including the holding of a constitutional convention, and the ruling Democratic Party found itself divided over the question of slavery, attempting to sidestep the issue by passing in state convention a resolution binding Democratic delegates to such a gathering to the position that the matter of slavery in Oregon be settled later by a vote of the people.

[13] While pro-slavery Democrat Joseph Lane was ultimately sent as the Territorial delegate to Congress, voting further down the ticket showed a Republican advance, with Republicans joining with so-called "soft" (free state) Democrats[14] to elect about a third of the delegates to the constitutional convention and 10 of the 30 members to the Oregon Territorial Legislature.

[18] Oregon would not be a slave state but rather one closed to black immigration — a law remaining on the books (albeit not in actual effect) into the 20th century.

[21] With the nation embroiled in war, pro-Union Democrats and Republicans put aside their differences at a fusion convention in April 1862, establishing themselves as the Union Party.

On October 21, 1861, with Congress out of session, Colonel Baker and his men met Confederate forces on a hill called Ball's Bluff just outside Washington, D.C.

[26] McNary helped pass legislation that led to the construction of the Columbia River's Bonneville Dam, and supported much of the New Deal.

McNary was also the Republican Party's vice presidential nominee in the 1940 election, as Wendell Willkie's running mate.

The walkout deepened the alignment of the party with right-wing militias, including Oregon 3 Percenters and Oath Keepers as well as pro-Trump social media.

"[33][34][35][36] According to the Pew Charitable Trusts, "rare walkouts are ones like that in Oregon, where lawmakers flee the state for several weeks or months.

These large events use a lot of political capital and show voters that those lawmakers might be sore losers and unwilling to negotiate.

"[37] Oregon Republicans continued such "walkouts" in 2021 to protest coronavirus restrictions and disable normal political processes, as well as organized groups to harass state inspectors doing their lawful work.

[46][47][48] "The Trump era seems only to have exacerbated the Oregon GOP’s embrace of its most extreme constituencies," writes the conservative National Review.

[57] In early February, state voter registration indicates a total of 11,000 registered Republicans in Oregon have left the party since Election Day.

[60] Senator Heard was succeeded as Chair first by Josephine County Commissioner Herman Baertschiger Jr., then restaurateur Justin Hwang.

The party's formal platform, adopted in 2015, expresses opposition to abortion and assisted suicide; support for mandatory minimum sentencing for violent offenders, truth-in-sentencing laws, and the death penalty; lower taxes; deregulation and minimal government intervention in the economy; opposition to same-sex marriage; repeal of the Patient Protection and Affordable Care Act; opposition for "amnesty" for undocumented immigrants; an individual right to keep and bear arms; and voter ID laws.

[61] The party's platform, amended in 2019, includes opposition to National Popular Vote Interstate Compact, advocacy of the arming of educational staff "to protect themselves and their students from violence" while opposing gun-free zones; asserting that "marriage is between one man and one woman" and that "there are only two sexes, male and female, based on a person’s biological sex at birth"; favoring that "all government business shall be conducted in English"; continuing repeal of Obamacare; asserting that "violent, radical, Islamic Jihadists and other groups have .

We will push to remove roadblocks to health care access and preserve Oregon’s natural environment while protecting the way of life of communities relying on these resources.

We will give Oregonians the freedom to recover financially from government-mandated shutdowns by fighting the state’s regulatory burdens and mandates.