Complex sentence: After the 1852 election the Whig Party quickly collapsed, and the members of the declining party failed to nominate a candidate for the next presidential race; it was soon replaced as the Democratic Party's primary opposition by the new Republican Party.
Split into simpler sentences: After the 1852 election, the Whig Party quickly collapsed, and the members of the declining party failed to nominate a candidate for the next presidential race. It was soon replaced as the Democratic Party's primary opposition by the new Republican Party.