History (in a nutshell)
The Republican Party, also known as the Grand Old Party (GOP), emerged from the great political realignment in the mid-1850s. It was founded in the Northern states by opponents of the Kansas-Nebraska Act, which allowed for the potential expansion of chattel slavery into the western territories (although it did not call for ending slavery in the Southern states).
The Republican Party first came to power in 1860 when it won control of both houses of Congress and its candidate, Abraham Lincoln, was elected President. In 1864, it united with the War Democrats to nominate Lincoln for a second term on the National Union Party ticket. Lincoln won and with a Republican Congress, the Thirteenth Amendment to the U.S. Constitution was passed to ban slavery.
The party's success created factionalism but was usually dominant over the Democrats. The Republican Civil War era program included free homestead farms, a federally subsidized transcontinental railroad, a national banking system, land grants for higher education, a wartime income tax and permanent high tariffs to promote industrial growth and high wages. By the 1870s, they adopted a hard money system based on the gold standard. They created the foundations of the modern welfare system through a program of pensions for Union veterans and they created a large national debt.
The Republicans became the party of big businesses and, in 1896, Theodore Roosevelt added more small business support by his embrace of trust busting. The party split when Roosevelt's hand-picked successor, William Howard Taft, and Roosevelt became enemies. When Taft defeated Roosevelt (who ran on a new Progressive Party ticket), most of Roosevelt's supporters returned to the GOP but found they did not agree with the new conservative economic thinking. This led to an ideologic shift to the right in the Republican Party. Throughout the 1920s, the Republican Party ran on platforms of business-oriented efficiency and high tariffs. These pro-business policies produced unprecedented wealth until the Wall Street Crash of 1929 started the Great Depression.
The New Deal era of Democrat Franklin D. Roosevelt controlled American politics for most of the next three decades (excluding the Republican president Dwight D. Eisenhower's terms). The Republican Party factionalized into a majority "Old Right" (based in the Midwest) and a liberal wing that supported much of the New Deal (based in the Northeast). The Old Right attacked the New Deal, saying it represented class warfare and socialism. Southern conservatives joined to form the conservation coalition, which dominated domestic issues until 1964. As Historian George H. Nash described:
"…The Republican Right at heart was counterrevolutionary, anti-collectivist, anti-Communist, anti-New Deal, passionately committed to limited government, free market economics and congressional (as opposed to executive) prerogatives. [They] were obliged to…wage a constant two-front war: against liberal Democrats from without and "me-too" Republicans from within."
Following the Civil Rights Act of 1964 and the Voting Rights Act of 1965, the party's core base shifted, with Southern states becoming more reliably Republican in presidential politics. After the Supreme Court's 1973 decision in Roe v. Wade, the Republican Party opposed abortion in its party platform and grew its support among evangelicals. Since 1976, liberalism has virtually faded out of the Republican Party, apart from a few Northeastern holdouts.
Platform
Republicans believe that individuals should take responsibility for their own circumstances. They believe that the private sector is more effective in helping the poor through charity than the government is through welfare programs and that these programs often cause government dependency.
Republicans believe that corporations should be able to establish their own employment practices (including benefits and wages) with the free market deciding the price of work. Since the 1920s, they have generally been opposed by labor unions.
While the modern Republican Party does include conservatives, centrists, fiscal conservatives, libertarians, neoconservatives, right-wing populists and social conservatives, the party can be broadly divided in the establishment and anti-establishment wings. Republican voters are split between "business conservatives" or "establishment conservatives" on one side and "steadfast conservatives" or "populist conservatives" on the other.
The following are the political positions held by Republican party candidates. Note: The GOP.org site does not clearly state these positions. These are extrapolated from the stances made on the site.
Economic Issues
Repeal and replace single-payer health care system ("socialized medicine") with one that puts patients and their doctors in charge of their health care decisions. Roll back regulations that have prevented market competition. Allow patients to buy insurance across state lines. Shut down lawsuits that have driven up the price of drugs.
Lower tax rates which will increase economic growth ("supply-side economics"). Oppose higher tax rates for higher earners because they unfairly target those who create jobs and wealth. Limit funding for tax enforcement and tax collection. Establish a smarter, simpler tax code.
Oppose increases in minimum wage because they hurt businesses by forcing them to cut and outsource jobs while passing on costs to consumers.
Make it easier for businesses to open up in the U.S. Support the Taft-Hartley Act of 1947, which gives workers the right not to participate in unions.
End dependency on Middle East oil by tapping into oil, natural gas, coal, hydropower, solar, wind, geothermal and nuclear power resources. Continue construction of the Keystone and Dakota Access Pipelines. Reject environmental regulations and the cap-and-trade policy to limit carbon emissions.
Advocate school choice, voucher and charter programs so parents can be chief decision makers. Decentralize education system.
Reform the Department of Veteran Affairs to end bureaucracy and streamline the process to prevent long waits for care.
Social Issues
Enact restrictions (such as purging voter rolls, limiting voting locations and prosecuting double voting) to prevent voter fraud.
Protect the sanctity of life by opposing elective abortion. Reject any government funding for abortion providers, notably Planned Parenthood. Give States the ability to exclude family-planning providers that provide abortion services from the Medicaid program. Propose new regulations to ensure Title X family planning funding does not go to projects that perform, support or refer patients for abortion. Establish new or expanded exemptions from the Obamacare contraceptive mandate based on religious beliefs or moral convictions. Reject federal funding of embryonic system stem cell research.
Allow each State to decide its own marriage policy. Define marriage as "natural marriage, the union of one man and one woman." Ban transgender individuals from service in the U.S. military. Oppose the inclusion of sexual preference in anti-discrimination statutes.
Secure the U.S. border and stop illegal immigration. Use extreme vetting procedures for people who are seeking to become American citizens.
Support gun ownership rights and oppose laws regulating guns.
Reject affirmative action for women and some minorities because it is not meritocratic and is counter-productive socially by only further promoting discrimination.
Foreign Policy
Promote democracy abroad, supporting unilateralism (U.S. to act without external support in matters of its national defense).
Restrict foreign aid as a means of asserting the national security and immigration interests of the U.S.