As candidates get past primaries, top donors are now pouring millions into general election campaigns

Billionaire hedge fund manager and philanthropist Tom Steyer speaks during a press conference at the National Press Club December 6, 2017 in Washington, DC. Steyer, founder of the 'Need To Impeach' initiative, presented legal grounds calling for the impeachment investigation of U.S. President Donald Trump during the press conference. 
Win McNamee | Getty Images News | Getty Images
Billionaire hedge fund manager and philanthropist Tom Steyer speaks during a press conference at the National Press Club December 6, 2017 in Washington, DC. Steyer, founder of the 'Need To Impeach' initiative, presented legal grounds calling for the impeachment investigation of U.S. President Donald Trump during the press conference. 

With primaries wrapped up in roughly 70 percent of congressional districts this week, campaign donors are beginning to turn to placing their bets on the general election.

Much of that money is coming from just a handful of the nation's richest donors, according to the latest campaign finance data.

Voters went to the polls in seven states Tuesday to pick party nominees in New York, Colorado, Maryland, South Carolina, Utah, Oklahoma and Mississippi.

So far, some $1.3 billion has been raised by 2,715 candidates for 435 House seats and 435 hopefuls in 35 Senate races. And some of the biggest checks are coming from just a handful of the wealthiest donors.

As of the latest monthly fillings, the 100 top individual donors to the upcoming House and Senate elections have contributed a combined $237 million, according to a tally of campaign finance records by the Center for Responsive Politics. Of that amount, roughly half came from just the top 12 donors on the list.

About 30 percent of that money went directly to candidates running for office. The rest, so-called soft contributions, went to groups that give money indirectly on behalf of individual candidates, the CRP data show.

So far, the top 100 donors are tilting slightly toward the left, according to the CRP. As of Monday, about $119 million had been spent on Democratic and liberal candidates and about $111 million on Republicans and conservatives.

At the very top of the list of individual donors, Tom Steyer has spent nearly $30 million in the current cycle to support Democratic and liberal candidates, according to the CRP. Steyer, a San Francisco investor who retired in 2012 to focus on politics, gave Democrats $75.5 million in 2014 and $91.1 million in 2016, according to CRP. Steyer is also leading an initiative called Need to Impeach, which is geared toward influencing Congress to impeach President Donald Trump.

Republicans are getting support from the second largest donor, Richard Uihlein, a Chicago businessman who founded a shipping company with his wife in 1980 after working for a family packaging business founded by his father.

So far in this election cycle, Uihlein and his wife have contributed nearly $27 million to Republican and conservative candidates. Uihlein donated $23.9 million in the 2016 cycle and $6.1 million in 2014, according to CRP.

So-called outside spending — money spent to favor one party or another without giving it directly to a candidate — has become the preferred conduit for campaign contributions, totaling roughly $1.4 billion of the $1.8 billion spent in the 2016 election cycle.

As of Monday, these "independent expenditures" amounted to about $158 million, the CRP reports, more than the $155 million raised in the entire 2014 midterm cycle. That amount doesn't include so-called dark money contributions, which are not required to be reported to the FEC.

Here's how much outside spending the 100 top individual donors have made their contributions so far, according to their campaign filings as of last Sunday.

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