US Election: Everything you need to know about Democrats and Republicans

• Dems and Reps have won every Presidential election since 1852

• In last century their ideologies have changed

• In the last few elections, Trump has shaken up the political scene further

• Get latest data, odds and volume of bets in our daily update

• View Betfair Exchange politics markets as you have never seen them before

Republicans and Democrats dominate US elections

As we covered in a previous Politics Explained article, Americans will find a number of decisions to make when they reach the ballot box this November.

While the presidential election is a political event that is closely followed across the world, voters will be choosing their representatives in Congress, as Governors, as well as for State and Local elected positions.

Yet one thing is consistent between all of them - two parties dominate the modern US political scene.

The Democratic and Republicans parties have between them won every Presidential election since 1852, and have controlled the US Congress since 1856.

How did US two party system come about?

There was a time when US politics was not dominated by these two political behemoths.

The United States' founding fathers initially rejected the idea of partisan politicians, yet by around the 1790s, key politicians began to organise into factions based on their key shared ideologies.

The first political party in the United States was the Federalist Party, which had its brief moment in the sun under Alexander Hamilton, now well-known to many as the focal point of the Broadway show Hamilton. The Democratic-Republican Party, founded by Thomas Jefferson and James Madison, took over the Federalist Party's dominance after the 1800 elections.

During Andrew Jackson's presidency, the Democratic-Republican Party split, and the Democratic Party as we know it today was born in 1828.

Its principal political opponent was the Whig Party which between 1833 and 1856 competed with the Democratic Party for power. Yet the Republican Party, founded in 1854 and broadly considered the successor to the Whigs, has been its principal rival ever since. Former Whigs including Abraham Lincoln and three other US Presidents around that time, won elections after switching to the Republican Party.

Unhappily ever after...

In the 20th Century, the dynamics between these two parties shifted dramatically to be much more recognisable to what we see today.

For instance, after the American Civil War (1861-65) until the 1940s, the Democratic Party broadly opposed civil rights reforms, to retain their strong showings with Southern white voters. Prior to the American Civil War, it also supported slavery or believed it was for the States to decide - almost unimaginable when you look at the party of today.

Yet after the Great Depression, Democratic President Franklin D. Roosevelt - known as FDR - embarked on the New Deal - a series of unprecedented reforms and public works programmes that are credited with propelling the Democratic Party to unparalleled heights. From 1933 to 1969 the Party held the Presidency for seven out of the nine terms, and controlled Congress for most of that time.

It also recast the Party as one of liberalism, and big government - while the Republicans were increasingly seen as the conservative party.

Yet in recent decades, the parties have become polarised along ideological faultlines.

Many readers will also remember the impact of the Tea Party movement, which spearheaded a more muscular conservatism during the presidency of Barack Obama. This is seen to have driven the Republican Party to adopt more radically conservative positions in recent years.

Meanwhile, the more centrist "Third Way" ideology of the Democrats in Bill Clinton's time, led to a new, more insurgent brand of leftist politicians.

In the United States, this is perhaps exemplified by Bernie Sanders, the independent Senator for Vermont who, in running for President under the Democrats in 2016 and 2020, has had an impact in shifting the political positions of the Democrats to the left alongside other prominent members of Congress such as Alexandria Ocasio-Cortez.

How Donald Trump changed the Republican Party

When Donald Trump won the Presidential nomination of the Republican Party in 2016, many veteran Republicans were shocked, some calling it a "hostile takeover" of their party.

Yet because of his strong personal support base - which has endured despite claims of insurrection following his disputing of the 2020 election results - the Republican Party has changed dramatically so as not to alienate the Trumpist coalition of voters.

In so doing, it has alienated many parts of its core base of voters.

Prominent Republicans who oppose Trump's presidential campaign are legion.They include Mike Pence, his former vice oresident. Other former vice presidents, including Dick Cheney - 2001 to 2009 under George W Bush - have even endorsed Democratic candidate Kamala Harris.

In a book in 2017, George H.W. Bush, who served as a Republican President before Bill Clinton, said that he had voted for Hillary Clinton over Donald Trump in the 2016 election.

His son, George W Bush, had voted for his former Secretary of State Condoleezza Rice in 2020 - as a "write-in" candidate, where a voter writes someone's name on the ballot paper who is not officially a candidate in the election.

It remains to be seen how the Republican Party will change further should Trump win the upcoming election.

For its part, the Democratic Party has positioned itself resolutely as a left-of-center party, and Joe Biden's Presidency built on a whole range of policies encouraged by more left-leaning segments of its membership.

Student loan forgiveness, strong positions on equal rights and abortion access, and huge spending programmes, have been key to his presidency. Yet on issues like the war in Israel-Gaza, the party's more left-leaning electorate has split in recent months.

This retrenching of positions has led to the incredibly tight election we see today.

Kamala Harris is still the 20/211.95 favourite to win November's election - she was as short as 5/61.84 last week - but her odds have drifted slightly.

Donald Trump, who met with UK Prime Minister Keir Starmer overnight, is now 11/102.11, having shortened from 5/42.25 in the past week.

The betting markets will continue to be tight all the way to the election. We'll be here all the way for more news and insight.

Now read the Betting.Betfair US election live blog